X-Git-Url: https://git.ucc.asn.au/?p=ipdf%2Fdocuments.git;a=blobdiff_plain;f=references%2Fparanoia.c;fp=references%2Fparanoia.c;h=1d3d55c52eb1f8719fc8758c7986d35a0bc11314;hp=0000000000000000000000000000000000000000;hb=fec4133faffded3f9af7cc29b69189e7d1f05f74;hpb=0f8e75393b859ea4b974948a86772b8abacebfc1 diff --git a/references/paranoia.c b/references/paranoia.c new file mode 100644 index 0000000..1d3d55c --- /dev/null +++ b/references/paranoia.c @@ -0,0 +1,2247 @@ +/* A C version of Kahan's Floating Point Test "Paranoia" + + Thos Sumner, UCSF, Feb. 1985 + David Gay, BTL, Jan. 1986 + + This is a rewrite from the Pascal version by + + B. A. Wichmann, 18 Jan. 1985 + + (and does NOT exhibit good C programming style). + + Adjusted to use Standard C headers 19 Jan. 1992 (dmg); + compile with -DKR_headers or insert +#define KR_headers + at the beginning if you have an old-style C compiler. + +(C) Apr 19 1983 in BASIC version by: + Professor W. M. Kahan, + 567 Evans Hall + Electrical Engineering & Computer Science Dept. + University of California + Berkeley, California 94720 + USA + +converted to Pascal by: + B. A. Wichmann + National Physical Laboratory + Teddington Middx + TW11 OLW + UK + +converted to C by: + + David M. Gay and Thos Sumner + AT&T Bell Labs Computer Center, Rm. U-76 + 600 Mountain Avenue University of California + Murray Hill, NJ 07974 San Francisco, CA 94143 + USA USA + +with simultaneous corrections to the Pascal source (reflected +in the Pascal source available over netlib). +[A couple of bug fixes from dgh = sun!dhough incorporated 31 July 1986.] + +Reports of results on various systems from all the versions +of Paranoia are being collected by Richard Karpinski at the +same address as Thos Sumner. This includes sample outputs, +bug reports, and criticisms. + +You may copy this program freely if you acknowledge its source. +Comments on the Pascal version to NPL, please. + + +The C version catches signals from floating-point exceptions. +If signal(SIGFPE,...) is unavailable in your environment, you may +#define NOSIGNAL to comment out the invocations of signal. + +This source file is too big for some C compilers, but may be split +into pieces. Comments containing "SPLIT" suggest convenient places +for this splitting. At the end of these comments is an "ed script" +(for the UNIX(tm) editor ed) that will do this splitting. + +By #defining Single when you compile this source, you may obtain +a single-precision C version of Paranoia. + + +The following is from the introductory commentary from Wichmann's work: + +The BASIC program of Kahan is written in Microsoft BASIC using many +facilities which have no exact analogy in Pascal. The Pascal +version below cannot therefore be exactly the same. Rather than be +a minimal transcription of the BASIC program, the Pascal coding +follows the conventional style of block-structured languages. Hence +the Pascal version could be useful in producing versions in other +structured languages. + +Rather than use identifiers of minimal length (which therefore have +little mnemonic significance), the Pascal version uses meaningful +identifiers as follows [Note: A few changes have been made for C]: + + +BASIC C BASIC C BASIC C + + A J S StickyBit + A1 AInverse J0 NoErrors T + B Radix [Failure] T0 Underflow + B1 BInverse J1 NoErrors T2 ThirtyTwo + B2 RadixD2 [SeriousDefect] T5 OneAndHalf + B9 BMinusU2 J2 NoErrors T7 TwentySeven + C [Defect] T8 TwoForty + C1 CInverse J3 NoErrors U OneUlp + D [Flaw] U0 UnderflowThreshold + D4 FourD K PageNo U1 + E0 L Milestone U2 + E1 M V + E2 Exp2 N V0 + E3 N1 V8 + E5 MinSqEr O Zero V9 + E6 SqEr O1 One W + E7 MaxSqEr O2 Two X + E8 O3 Three X1 + E9 O4 Four X8 + F1 MinusOne O5 Five X9 Random1 + F2 Half O8 Eight Y + F3 Third O9 Nine Y1 + F6 P Precision Y2 + F9 Q Y9 Random2 + G1 GMult Q8 Z + G2 GDiv Q9 Z0 PseudoZero + G3 GAddSub R Z1 + H R1 RMult Z2 + H1 HInverse R2 RDiv Z9 + I R3 RAddSub + IO NoTrials R4 RSqrt + I3 IEEE R9 Random9 + + SqRWrng + +All the variables in BASIC are true variables and in consequence, +the program is more difficult to follow since the "constants" must +be determined (the glossary is very helpful). The Pascal version +uses Real constants, but checks are added to ensure that the values +are correctly converted by the compiler. + +The major textual change to the Pascal version apart from the +identifiersis that named procedures are used, inserting parameters +wherehelpful. New procedures are also introduced. The +correspondence is as follows: + + +BASIC Pascal +lines + + 90- 140 Pause + 170- 250 Instructions + 380- 460 Heading + 480- 670 Characteristics + 690- 870 History +2940-2950 Random +3710-3740 NewD +4040-4080 DoesYequalX +4090-4110 PrintIfNPositive +4640-4850 TestPartialUnderflow + +=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*= + +Below is an "ed script" that splits para.c into 10 files +of the form part[1-8].c, subs.c, and msgs.c, plus a header +file, paranoia.h, that these files require. + +r paranoia.c +$ +?SPLIT + .d ++d +-,$w msgs.c +-,$d +?SPLIT + .d ++d +-,$w subs.c +-,$d +?part8 ++d +?include + .,$w part8.c + .,$d +-d +?part7 ++d +?include + .,$w part7.c + .,$d +-d +?part6 ++d +?include + .,$w part6.c + .,$d +-d +?part5 ++d +?include + .,$w part5.c + .,$d +-d +?part4 ++d +?include + .,$w part4.c + .,$d +-d +?part3 ++d +?include + .,$w part3.c + .,$d +-d +?part2 ++d +?include + .,$w part2.c + .,$d +?SPLIT + .d +1,/^#include/-1d +1,$w part1.c +/Computed constants/,$d +1,$s/^int/extern &/ +1,$s/^FLOAT/extern &/ +1,$s/^char/extern &/ +1,$s! = .*!;! +/^Guard/,/^Round/s/^/extern / +/^jmp_buf/s/^/extern / +/^Sig_type/s/^/extern / +s/$/\ +extern void sigfpe(INT);/ +w paranoia.h +q + +*/ + +#include +#ifndef NOSIGNAL +#include +#endif +#include + +#ifdef Single +#define FLOAT float +#define FABS(x) (float)fabs((double)(x)) +#define FLOOR(x) (float)floor((double)(x)) +#define LOG(x) (float)log((double)(x)) +#define POW(x,y) (float)pow((double)(x),(double)(y)) +#define SQRT(x) (float)sqrt((double)(x)) +#else +#define FLOAT double +#define FABS(x) fabs(x) +#define FLOOR(x) floor(x) +#define LOG(x) log(x) +#define POW(x,y) pow(x,y) +#define SQRT(x) sqrt(x) +#endif + +jmp_buf ovfl_buf; +#ifdef KR_headers +#define VOID /* void */ +#define INT /* int */ +#define FP /* FLOAT */ +#define CHARP /* char * */ +#define CHARPP /* char ** */ +extern double fabs(), floor(), log(), pow(), sqrt(); +extern void exit(); +typedef void (*Sig_type)(); +FLOAT Sign(), Random(); +extern void BadCond(); +extern void SqXMinX(); +extern void TstCond(); +extern void notify(); +extern int read(); +#else +#define VOID void +#define INT int +#define FP FLOAT +#define CHARP char * +#define CHARPP char ** +#ifdef __STDC__ +#include +#include +#else +#ifdef __cplusplus +extern "C" { +#endif +extern double fabs(double), floor(double), log(double); +extern double pow(double,double), sqrt(double); +extern void exit(INT); +#ifdef __cplusplus + } +#endif +#endif +typedef void (*Sig_type)(int); +FLOAT Sign(FLOAT), Random(void); +extern void BadCond(int, char*); +extern void SqXMinX(int); +extern void TstCond(int, int, char*); +extern void notify(char*); +extern int read(int, char*, int); +#endif +#undef V9 +extern void Characteristics(VOID); +extern void Heading(VOID); +extern void History(VOID); +extern void Instructions(VOID); +extern void IsYeqX(VOID); +extern void NewD(VOID); +extern void Pause(VOID); +extern void PrintIfNPositive(VOID); +extern void SR3750(VOID); +extern void SR3980(VOID); +extern void TstPtUf(VOID); + +Sig_type sigsave; + +#define KEYBOARD 0 + +FLOAT Radix, BInvrse, RadixD2, BMinusU2; + +/*Small floating point constants.*/ +FLOAT Zero = 0.0; +FLOAT Half = 0.5; +FLOAT One = 1.0; +FLOAT Two = 2.0; +FLOAT Three = 3.0; +FLOAT Four = 4.0; +FLOAT Five = 5.0; +FLOAT Eight = 8.0; +FLOAT Nine = 9.0; +FLOAT TwentySeven = 27.0; +FLOAT ThirtyTwo = 32.0; +FLOAT TwoForty = 240.0; +FLOAT MinusOne = -1.0; +FLOAT OneAndHalf = 1.5; +/*Integer constants*/ +int NoTrials = 20; /*Number of tests for commutativity. */ +#define False 0 +#define True 1 + +/* Definitions for declared types + Guard == (Yes, No); + Rounding == (Chopped, Rounded, Other); + Message == packed array [1..40] of char; + Class == (Flaw, Defect, Serious, Failure); + */ +#define Yes 1 +#define No 0 +#define Chopped 2 +#define Rounded 1 +#define Other 0 +#define Flaw 3 +#define Defect 2 +#define Serious 1 +#define Failure 0 +typedef int Guard, Rounding, Class; +typedef char Message; + +/* Declarations of Variables */ +int Indx; +char ch[8]; +FLOAT AInvrse, A1; +FLOAT C, CInvrse; +FLOAT D, FourD; +FLOAT E0, E1, Exp2, E3, MinSqEr; +FLOAT SqEr, MaxSqEr, E9; +FLOAT Third; +FLOAT F6, F9; +FLOAT H, HInvrse; +int I; +FLOAT StickyBit, J; +FLOAT MyZero; +FLOAT Precision; +FLOAT Q, Q9; +FLOAT R, Random9; +FLOAT T, Underflow, S; +FLOAT OneUlp, UfThold, U1, U2; +FLOAT V, V0, V9; +FLOAT W; +FLOAT X, X1, X2, X8, Random1; +FLOAT Y, Y1, Y2, Random2; +FLOAT Z, PseudoZero, Z1, Z2, Z9; +int ErrCnt[4]; +int fpecount; +int Milestone; +int PageNo; +int M, N, N1; +Guard GMult, GDiv, GAddSub; +Rounding RMult, RDiv, RAddSub, RSqrt; +int Break, Done, NotMonot, Monot, Anomaly, IEEE, + SqRWrng, UfNGrad; +/* Computed constants. */ +/*U1 gap below 1.0, i.e, 1.0-U1 is next number below 1.0 */ +/*U2 gap above 1.0, i.e, 1.0+U2 is next number above 1.0 */ + +/* floating point exception receiver */ + void +sigfpe(INT x) +{ + fpecount++; + printf("\n* * * FLOATING-POINT ERROR %d * * *\n", x); + fflush(stdout); + if (sigsave) { +#ifndef NOSIGNAL + signal(SIGFPE, sigsave); +#endif + sigsave = 0; + longjmp(ovfl_buf, 1); + } + exit(1); +} + +main(VOID) +{ + /* First two assignments use integer right-hand sides. */ + Zero = 0; + One = 1; + Two = One + One; + Three = Two + One; + Four = Three + One; + Five = Four + One; + Eight = Four + Four; + Nine = Three * Three; + TwentySeven = Nine * Three; + ThirtyTwo = Four * Eight; + TwoForty = Four * Five * Three * Four; + MinusOne = -One; + Half = One / Two; + OneAndHalf = One + Half; + ErrCnt[Failure] = 0; + ErrCnt[Serious] = 0; + ErrCnt[Defect] = 0; + ErrCnt[Flaw] = 0; + PageNo = 1; + /*=============================================*/ + Milestone = 0; + /*=============================================*/ +#ifndef NOSIGNAL + signal(SIGFPE, sigfpe); +#endif + Instructions(); + Pause(); + Heading(); + Pause(); + Characteristics(); + Pause(); + History(); + Pause(); + /*=============================================*/ + Milestone = 7; + /*=============================================*/ + printf("Program is now RUNNING tests on small integers:\n"); + + TstCond (Failure, (Zero + Zero == Zero) && (One - One == Zero) + && (One > Zero) && (One + One == Two), + "0+0 != 0, 1-1 != 0, 1 <= 0, or 1+1 != 2"); + Z = - Zero; + if (Z != 0.0) { + ErrCnt[Failure] = ErrCnt[Failure] + 1; + printf("Comparison alleges that -0.0 is Non-zero!\n"); + U2 = 0.001; + Radix = 1; + TstPtUf(); + } + TstCond (Failure, (Three == Two + One) && (Four == Three + One) + && (Four + Two * (- Two) == Zero) + && (Four - Three - One == Zero), + "3 != 2+1, 4 != 3+1, 4+2*(-2) != 0, or 4-3-1 != 0"); + TstCond (Failure, (MinusOne == (0 - One)) + && (MinusOne + One == Zero ) && (One + MinusOne == Zero) + && (MinusOne + FABS(One) == Zero) + && (MinusOne + MinusOne * MinusOne == Zero), + "-1+1 != 0, (-1)+abs(1) != 0, or -1+(-1)*(-1) != 0"); + TstCond (Failure, Half + MinusOne + Half == Zero, + "1/2 + (-1) + 1/2 != 0"); + /*=============================================*/ + /*SPLIT + { + extern void part2(VOID), part3(VOID), part4(VOID), + part5(VOID), part6(VOID), part7(VOID); + int part8(VOID); + + part2(); + part3(); + part4(); + part5(); + part6(); + part7(); + return part8(); + } + } +#include "paranoia.h" +void part2(VOID){ +*/ + Milestone = 10; + /*=============================================*/ + TstCond (Failure, (Nine == Three * Three) + && (TwentySeven == Nine * Three) && (Eight == Four + Four) + && (ThirtyTwo == Eight * Four) + && (ThirtyTwo - TwentySeven - Four - One == Zero), + "9 != 3*3, 27 != 9*3, 32 != 8*4, or 32-27-4-1 != 0"); + TstCond (Failure, (Five == Four + One) && + (TwoForty == Four * Five * Three * Four) + && (TwoForty / Three - Four * Four * Five == Zero) + && ( TwoForty / Four - Five * Three * Four == Zero) + && ( TwoForty / Five - Four * Three * Four == Zero), + "5 != 4+1, 240/3 != 80, 240/4 != 60, or 240/5 != 48"); + if (ErrCnt[Failure] == 0) { + printf("-1, 0, 1/2, 1, 2, 3, 4, 5, 9, 27, 32 & 240 are O.K.\n"); + printf("\n"); + } + printf("Searching for Radix and Precision.\n"); + W = One; + do { + W = W + W; + Y = W + One; + Z = Y - W; + Y = Z - One; + } while (MinusOne + FABS(Y) < Zero); + /*.. now W is just big enough that |((W+1)-W)-1| >= 1 ...*/ + Precision = Zero; + Y = One; + do { + Radix = W + Y; + Y = Y + Y; + Radix = Radix - W; + } while ( Radix == Zero); + if (Radix < Two) Radix = One; + printf("Radix = %f .\n", Radix); + if (Radix != 1) { + W = One; + do { + Precision = Precision + One; + W = W * Radix; + Y = W + One; + } while ((Y - W) == One); + } + /*... now W == Radix^Precision is barely too big to satisfy (W+1)-W == 1 + ...*/ + U1 = One / W; + U2 = Radix * U1; + printf("Closest relative separation found is U1 = %.7e .\n\n", U1); + printf("Recalculating radix and precision\n "); + + /*save old values*/ + E0 = Radix; + E1 = U1; + E9 = U2; + E3 = Precision; + + X = Four / Three; + Third = X - One; + F6 = Half - Third; + X = F6 + F6; + X = FABS(X - Third); + if (X < U2) X = U2; + + /*... now X = (unknown no.) ulps of 1+...*/ + do { + U2 = X; + Y = Half * U2 + ThirtyTwo * U2 * U2; + Y = One + Y; + X = Y - One; + } while ( ! ((U2 <= X) || (X <= Zero))); + + /*... now U2 == 1 ulp of 1 + ... */ + X = Two / Three; + F6 = X - Half; + Third = F6 + F6; + X = Third - Half; + X = FABS(X + F6); + if (X < U1) X = U1; + + /*... now X == (unknown no.) ulps of 1 -... */ + do { + U1 = X; + Y = Half * U1 + ThirtyTwo * U1 * U1; + Y = Half - Y; + X = Half + Y; + Y = Half - X; + X = Half + Y; + } while ( ! ((U1 <= X) || (X <= Zero))); + /*... now U1 == 1 ulp of 1 - ... */ + if (U1 == E1) printf("confirms closest relative separation U1 .\n"); + else printf("gets better closest relative separation U1 = %.7e .\n", U1); + W = One / U1; + F9 = (Half - U1) + Half; + Radix = FLOOR(0.01 + U2 / U1); + if (Radix == E0) printf("Radix confirmed.\n"); + else printf("MYSTERY: recalculated Radix = %.7e .\n", Radix); + TstCond (Defect, Radix <= Eight + Eight, + "Radix is too big: roundoff problems"); + TstCond (Flaw, (Radix == Two) || (Radix == 10) + || (Radix == One), "Radix is not as good as 2 or 10"); + /*=============================================*/ + Milestone = 20; + /*=============================================*/ + TstCond (Failure, F9 - Half < Half, + "(1-U1)-1/2 < 1/2 is FALSE, prog. fails?"); + X = F9; + I = 1; + Y = X - Half; + Z = Y - Half; + TstCond (Failure, (X != One) + || (Z == Zero), "Comparison is fuzzy,X=1 but X-1/2-1/2 != 0"); + X = One + U2; + I = 0; + /*=============================================*/ + Milestone = 25; + /*=============================================*/ + /*... BMinusU2 = nextafter(Radix, 0) */ + BMinusU2 = Radix - One; + BMinusU2 = (BMinusU2 - U2) + One; + /* Purify Integers */ + if (Radix != One) { + X = - TwoForty * LOG(U1) / LOG(Radix); + Y = FLOOR(Half + X); + if (FABS(X - Y) * Four < One) X = Y; + Precision = X / TwoForty; + Y = FLOOR(Half + Precision); + if (FABS(Precision - Y) * TwoForty < Half) Precision = Y; + } + if ((Precision != FLOOR(Precision)) || (Radix == One)) { + printf("Precision cannot be characterized by an Integer number\n"); + printf("of significant digits but, by itself, this is a minor flaw.\n"); + } + if (Radix == One) + printf("logarithmic encoding has precision characterized solely by U1.\n"); + else printf("The number of significant digits of the Radix is %f .\n", + Precision); + TstCond (Serious, U2 * Nine * Nine * TwoForty < One, + "Precision worse than 5 decimal figures "); + /*=============================================*/ + Milestone = 30; + /*=============================================*/ + /* Test for extra-precise subepressions */ + X = FABS(((Four / Three - One) - One / Four) * Three - One / Four); + do { + Z2 = X; + X = (One + (Half * Z2 + ThirtyTwo * Z2 * Z2)) - One; + } while ( ! ((Z2 <= X) || (X <= Zero))); + X = Y = Z = FABS((Three / Four - Two / Three) * Three - One / Four); + do { + Z1 = Z; + Z = (One / Two - ((One / Two - (Half * Z1 + ThirtyTwo * Z1 * Z1)) + + One / Two)) + One / Two; + } while ( ! ((Z1 <= Z) || (Z <= Zero))); + do { + do { + Y1 = Y; + Y = (Half - ((Half - (Half * Y1 + ThirtyTwo * Y1 * Y1)) + Half + )) + Half; + } while ( ! ((Y1 <= Y) || (Y <= Zero))); + X1 = X; + X = ((Half * X1 + ThirtyTwo * X1 * X1) - F9) + F9; + } while ( ! ((X1 <= X) || (X <= Zero))); + if ((X1 != Y1) || (X1 != Z1)) { + BadCond(Serious, "Disagreements among the values X1, Y1, Z1,\n"); + printf("respectively %.7e, %.7e, %.7e,\n", X1, Y1, Z1); + printf("are symptoms of inconsistencies introduced\n"); + printf("by extra-precise evaluation of arithmetic subexpressions.\n"); + notify("Possibly some part of this"); + if ((X1 == U1) || (Y1 == U1) || (Z1 == U1)) printf( + "That feature is not tested further by this program.\n") ; + } + else { + if ((Z1 != U1) || (Z2 != U2)) { + if ((Z1 >= U1) || (Z2 >= U2)) { + BadCond(Failure, ""); + notify("Precision"); + printf("\tU1 = %.7e, Z1 - U1 = %.7e\n",U1,Z1-U1); + printf("\tU2 = %.7e, Z2 - U2 = %.7e\n",U2,Z2-U2); + } + else { + if ((Z1 <= Zero) || (Z2 <= Zero)) { + printf("Because of unusual Radix = %f", Radix); + printf(", or exact rational arithmetic a result\n"); + printf("Z1 = %.7e, or Z2 = %.7e ", Z1, Z2); + notify("of an\nextra-precision"); + } + if (Z1 != Z2 || Z1 > Zero) { + X = Z1 / U1; + Y = Z2 / U2; + if (Y > X) X = Y; + Q = - LOG(X); + printf("Some subexpressions appear to be calculated extra\n"); + printf("precisely with about %g extra B-digits, i.e.\n", + (Q / LOG(Radix))); + printf("roughly %g extra significant decimals.\n", + Q / LOG(10.)); + } + printf("That feature is not tested further by this program.\n"); + } + } + } + Pause(); + /*=============================================*/ + /*SPLIT + } +#include "paranoia.h" +void part3(VOID){ +*/ + Milestone = 35; + /*=============================================*/ + if (Radix >= Two) { + X = W / (Radix * Radix); + Y = X + One; + Z = Y - X; + T = Z + U2; + X = T - Z; + TstCond (Failure, X == U2, + "Subtraction is not normalized X=Y,X+Z != Y+Z!"); + if (X == U2) printf( + "Subtraction appears to be normalized, as it should be."); + } + printf("\nChecking for guard digit in *, /, and -.\n"); + Y = F9 * One; + Z = One * F9; + X = F9 - Half; + Y = (Y - Half) - X; + Z = (Z - Half) - X; + X = One + U2; + T = X * Radix; + R = Radix * X; + X = T - Radix; + X = X - Radix * U2; + T = R - Radix; + T = T - Radix * U2; + X = X * (Radix - One); + T = T * (Radix - One); + if ((X == Zero) && (Y == Zero) && (Z == Zero) && (T == Zero)) GMult = Yes; + else { + GMult = No; + TstCond (Serious, False, + "* lacks a Guard Digit, so 1*X != X"); + } + Z = Radix * U2; + X = One + Z; + Y = FABS((X + Z) - X * X) - U2; + X = One - U2; + Z = FABS((X - U2) - X * X) - U1; + TstCond (Failure, (Y <= Zero) + && (Z <= Zero), "* gets too many final digits wrong.\n"); + Y = One - U2; + X = One + U2; + Z = One / Y; + Y = Z - X; + X = One / Three; + Z = Three / Nine; + X = X - Z; + T = Nine / TwentySeven; + Z = Z - T; + TstCond(Defect, X == Zero && Y == Zero && Z == Zero, + "Division lacks a Guard Digit, so error can exceed 1 ulp\n\ +or 1/3 and 3/9 and 9/27 may disagree"); + Y = F9 / One; + X = F9 - Half; + Y = (Y - Half) - X; + X = One + U2; + T = X / One; + X = T - X; + if ((X == Zero) && (Y == Zero) && (Z == Zero)) GDiv = Yes; + else { + GDiv = No; + TstCond (Serious, False, + "Division lacks a Guard Digit, so X/1 != X"); + } + X = One / (One + U2); + Y = X - Half - Half; + TstCond (Serious, Y < Zero, + "Computed value of 1/1.000..1 >= 1"); + X = One - U2; + Y = One + Radix * U2; + Z = X * Radix; + T = Y * Radix; + R = Z / Radix; + StickyBit = T / Radix; + X = R - X; + Y = StickyBit - Y; + TstCond (Failure, X == Zero && Y == Zero, + "* and/or / gets too many last digits wrong"); + Y = One - U1; + X = One - F9; + Y = One - Y; + T = Radix - U2; + Z = Radix - BMinusU2; + T = Radix - T; + if ((X == U1) && (Y == U1) && (Z == U2) && (T == U2)) GAddSub = Yes; + else { + GAddSub = No; + TstCond (Serious, False, + "- lacks Guard Digit, so cancellation is obscured"); + } + if (F9 != One && F9 - One >= Zero) { + BadCond(Serious, "comparison alleges (1-U1) < 1 although\n"); + printf(" subtraction yields (1-U1) - 1 = 0 , thereby vitiating\n"); + printf(" such precautions against division by zero as\n"); + printf(" ... if (X == 1.0) {.....} else {.../(X-1.0)...}\n"); + } + if (GMult == Yes && GDiv == Yes && GAddSub == Yes) printf( + " *, /, and - appear to have guard digits, as they should.\n"); + /*=============================================*/ + Milestone = 40; + /*=============================================*/ + Pause(); + printf("Checking rounding on multiply, divide and add/subtract.\n"); + RMult = Other; + RDiv = Other; + RAddSub = Other; + RadixD2 = Radix / Two; + A1 = Two; + Done = False; + do { + AInvrse = Radix; + do { + X = AInvrse; + AInvrse = AInvrse / A1; + } while ( ! (FLOOR(AInvrse) != AInvrse)); + Done = (X == One) || (A1 > Three); + if (! Done) A1 = Nine + One; + } while ( ! (Done)); + if (X == One) A1 = Radix; + AInvrse = One / A1; + X = A1; + Y = AInvrse; + Done = False; + do { + Z = X * Y - Half; + TstCond (Failure, Z == Half, + "X * (1/X) differs from 1"); + Done = X == Radix; + X = Radix; + Y = One / X; + } while ( ! (Done)); + Y2 = One + U2; + Y1 = One - U2; + X = OneAndHalf - U2; + Y = OneAndHalf + U2; + Z = (X - U2) * Y2; + T = Y * Y1; + Z = Z - X; + T = T - X; + X = X * Y2; + Y = (Y + U2) * Y1; + X = X - OneAndHalf; + Y = Y - OneAndHalf; + if ((X == Zero) && (Y == Zero) && (Z == Zero) && (T <= Zero)) { + X = (OneAndHalf + U2) * Y2; + Y = OneAndHalf - U2 - U2; + Z = OneAndHalf + U2 + U2; + T = (OneAndHalf - U2) * Y1; + X = X - (Z + U2); + StickyBit = Y * Y1; + S = Z * Y2; + T = T - Y; + Y = (U2 - Y) + StickyBit; + Z = S - (Z + U2 + U2); + StickyBit = (Y2 + U2) * Y1; + Y1 = Y2 * Y1; + StickyBit = StickyBit - Y2; + Y1 = Y1 - Half; + if ((X == Zero) && (Y == Zero) && (Z == Zero) && (T == Zero) + && ( StickyBit == Zero) && (Y1 == Half)) { + RMult = Rounded; + printf("Multiplication appears to round correctly.\n"); + } + else if ((X + U2 == Zero) && (Y < Zero) && (Z + U2 == Zero) + && (T < Zero) && (StickyBit + U2 == Zero) + && (Y1 < Half)) { + RMult = Chopped; + printf("Multiplication appears to chop.\n"); + } + else printf("* is neither chopped nor correctly rounded.\n"); + if ((RMult == Rounded) && (GMult == No)) notify("Multiplication"); + } + else printf("* is neither chopped nor correctly rounded.\n"); + /*=============================================*/ + Milestone = 45; + /*=============================================*/ + Y2 = One + U2; + Y1 = One - U2; + Z = OneAndHalf + U2 + U2; + X = Z / Y2; + T = OneAndHalf - U2 - U2; + Y = (T - U2) / Y1; + Z = (Z + U2) / Y2; + X = X - OneAndHalf; + Y = Y - T; + T = T / Y1; + Z = Z - (OneAndHalf + U2); + T = (U2 - OneAndHalf) + T; + if (! ((X > Zero) || (Y > Zero) || (Z > Zero) || (T > Zero))) { + X = OneAndHalf / Y2; + Y = OneAndHalf - U2; + Z = OneAndHalf + U2; + X = X - Y; + T = OneAndHalf / Y1; + Y = Y / Y1; + T = T - (Z + U2); + Y = Y - Z; + Z = Z / Y2; + Y1 = (Y2 + U2) / Y2; + Z = Z - OneAndHalf; + Y2 = Y1 - Y2; + Y1 = (F9 - U1) / F9; + if ((X == Zero) && (Y == Zero) && (Z == Zero) && (T == Zero) + && (Y2 == Zero) && (Y2 == Zero) + && (Y1 - Half == F9 - Half )) { + RDiv = Rounded; + printf("Division appears to round correctly.\n"); + if (GDiv == No) notify("Division"); + } + else if ((X < Zero) && (Y < Zero) && (Z < Zero) && (T < Zero) + && (Y2 < Zero) && (Y1 - Half < F9 - Half)) { + RDiv = Chopped; + printf("Division appears to chop.\n"); + } + } + if (RDiv == Other) printf("/ is neither chopped nor correctly rounded.\n"); + BInvrse = One / Radix; + TstCond (Failure, (BInvrse * Radix - Half == Half), + "Radix * ( 1 / Radix ) differs from 1"); + /*=============================================*/ + /*SPLIT + } +#include "paranoia.h" +void part4(VOID){ +*/ + Milestone = 50; + /*=============================================*/ + TstCond (Failure, ((F9 + U1) - Half == Half) + && ((BMinusU2 + U2 ) - One == Radix - One), + "Incomplete carry-propagation in Addition"); + X = One - U1 * U1; + Y = One + U2 * (One - U2); + Z = F9 - Half; + X = (X - Half) - Z; + Y = Y - One; + if ((X == Zero) && (Y == Zero)) { + RAddSub = Chopped; + printf("Add/Subtract appears to be chopped.\n"); + } + if (GAddSub == Yes) { + X = (Half + U2) * U2; + Y = (Half - U2) * U2; + X = One + X; + Y = One + Y; + X = (One + U2) - X; + Y = One - Y; + if ((X == Zero) && (Y == Zero)) { + X = (Half + U2) * U1; + Y = (Half - U2) * U1; + X = One - X; + Y = One - Y; + X = F9 - X; + Y = One - Y; + if ((X == Zero) && (Y == Zero)) { + RAddSub = Rounded; + printf("Addition/Subtraction appears to round correctly.\n"); + if (GAddSub == No) notify("Add/Subtract"); + } + else printf("Addition/Subtraction neither rounds nor chops.\n"); + } + else printf("Addition/Subtraction neither rounds nor chops.\n"); + } + else printf("Addition/Subtraction neither rounds nor chops.\n"); + S = One; + X = One + Half * (One + Half); + Y = (One + U2) * Half; + Z = X - Y; + T = Y - X; + StickyBit = Z + T; + if (StickyBit != Zero) { + S = Zero; + BadCond(Flaw, "(X - Y) + (Y - X) is non zero!\n"); + } + StickyBit = Zero; + if ((GMult == Yes) && (GDiv == Yes) && (GAddSub == Yes) + && (RMult == Rounded) && (RDiv == Rounded) + && (RAddSub == Rounded) && (FLOOR(RadixD2) == RadixD2)) { + printf("Checking for sticky bit.\n"); + X = (Half + U1) * U2; + Y = Half * U2; + Z = One + Y; + T = One + X; + if ((Z - One <= Zero) && (T - One >= U2)) { + Z = T + Y; + Y = Z - X; + if ((Z - T >= U2) && (Y - T == Zero)) { + X = (Half + U1) * U1; + Y = Half * U1; + Z = One - Y; + T = One - X; + if ((Z - One == Zero) && (T - F9 == Zero)) { + Z = (Half - U1) * U1; + T = F9 - Z; + Q = F9 - Y; + if ((T - F9 == Zero) && (F9 - U1 - Q == Zero)) { + Z = (One + U2) * OneAndHalf; + T = (OneAndHalf + U2) - Z + U2; + X = One + Half / Radix; + Y = One + Radix * U2; + Z = X * Y; + if (T == Zero && X + Radix * U2 - Z == Zero) { + if (Radix != Two) { + X = Two + U2; + Y = X / Two; + if ((Y - One == Zero)) StickyBit = S; + } + else StickyBit = S; + } + } + } + } + } + } + if (StickyBit == One) printf("Sticky bit apparently used correctly.\n"); + else printf("Sticky bit used incorrectly or not at all.\n"); + TstCond (Flaw, !(GMult == No || GDiv == No || GAddSub == No || + RMult == Other || RDiv == Other || RAddSub == Other), + "lack(s) of guard digits or failure(s) to correctly round or chop\n\ +(noted above) count as one flaw in the final tally below"); + /*=============================================*/ + Milestone = 60; + /*=============================================*/ + printf("\n"); + printf("Does Multiplication commute? "); + printf("Testing on %d random pairs.\n", NoTrials); + Random9 = SQRT(3.0); + Random1 = Third; + I = 1; + do { + X = Random(); + Y = Random(); + Z9 = Y * X; + Z = X * Y; + Z9 = Z - Z9; + I = I + 1; + } while ( ! ((I > NoTrials) || (Z9 != Zero))); + if (I == NoTrials) { + Random1 = One + Half / Three; + Random2 = (U2 + U1) + One; + Z = Random1 * Random2; + Y = Random2 * Random1; + Z9 = (One + Half / Three) * ((U2 + U1) + One) - (One + Half / + Three) * ((U2 + U1) + One); + } + if (! ((I == NoTrials) || (Z9 == Zero))) + BadCond(Defect, "X * Y == Y * X trial fails.\n"); + else printf(" No failures found in %d integer pairs.\n", NoTrials); + /*=============================================*/ + Milestone = 70; + /*=============================================*/ + printf("\nRunning test of square root(x).\n"); + TstCond (Failure, (Zero == SQRT(Zero)) + && (- Zero == SQRT(- Zero)) + && (One == SQRT(One)), "Square root of 0.0, -0.0 or 1.0 wrong"); + MinSqEr = Zero; + MaxSqEr = Zero; + J = Zero; + X = Radix; + OneUlp = U2; + SqXMinX (Serious); + X = BInvrse; + OneUlp = BInvrse * U1; + SqXMinX (Serious); + X = U1; + OneUlp = U1 * U1; + SqXMinX (Serious); + if (J != Zero) Pause(); + printf("Testing if sqrt(X * X) == X for %d Integers X.\n", NoTrials); + J = Zero; + X = Two; + Y = Radix; + if ((Radix != One)) do { + X = Y; + Y = Radix * Y; + } while ( ! ((Y - X >= NoTrials))); + OneUlp = X * U2; + I = 1; + while (I <= NoTrials) { + X = X + One; + SqXMinX (Defect); + if (J > Zero) break; + I = I + 1; + } + printf("Test for sqrt monotonicity.\n"); + I = - 1; + X = BMinusU2; + Y = Radix; + Z = Radix + Radix * U2; + NotMonot = False; + Monot = False; + while ( ! (NotMonot || Monot)) { + I = I + 1; + X = SQRT(X); + Q = SQRT(Y); + Z = SQRT(Z); + if ((X > Q) || (Q > Z)) NotMonot = True; + else { + Q = FLOOR(Q + Half); + if (!(I > 0 || Radix == Q * Q)) Monot = True; + else if (I > 0) { + if (I > 1) Monot = True; + else { + Y = Y * BInvrse; + X = Y - U1; + Z = Y + U1; + } + } + else { + Y = Q; + X = Y - U2; + Z = Y + U2; + } + } + } + if (Monot) printf("sqrt has passed a test for Monotonicity.\n"); + else { + BadCond(Defect, ""); + printf("sqrt(X) is non-monotonic for X near %.7e .\n", Y); + } + /*=============================================*/ + /*SPLIT + } +#include "paranoia.h" +void part5(VOID){ +*/ + Milestone = 80; + /*=============================================*/ + MinSqEr = MinSqEr + Half; + MaxSqEr = MaxSqEr - Half; + Y = (SQRT(One + U2) - One) / U2; + SqEr = (Y - One) + U2 / Eight; + if (SqEr > MaxSqEr) MaxSqEr = SqEr; + SqEr = Y + U2 / Eight; + if (SqEr < MinSqEr) MinSqEr = SqEr; + Y = ((SQRT(F9) - U2) - (One - U2)) / U1; + SqEr = Y + U1 / Eight; + if (SqEr > MaxSqEr) MaxSqEr = SqEr; + SqEr = (Y + One) + U1 / Eight; + if (SqEr < MinSqEr) MinSqEr = SqEr; + OneUlp = U2; + X = OneUlp; + for( Indx = 1; Indx <= 3; ++Indx) { + Y = SQRT((X + U1 + X) + F9); + Y = ((Y - U2) - ((One - U2) + X)) / OneUlp; + Z = ((U1 - X) + F9) * Half * X * X / OneUlp; + SqEr = (Y + Half) + Z; + if (SqEr < MinSqEr) MinSqEr = SqEr; + SqEr = (Y - Half) + Z; + if (SqEr > MaxSqEr) MaxSqEr = SqEr; + if (((Indx == 1) || (Indx == 3))) + X = OneUlp * Sign (X) * FLOOR(Eight / (Nine * SQRT(OneUlp))); + else { + OneUlp = U1; + X = - OneUlp; + } + } + /*=============================================*/ + Milestone = 85; + /*=============================================*/ + SqRWrng = False; + Anomaly = False; + RSqrt = Other; /* ~dgh */ + if (Radix != One) { + printf("Testing whether sqrt is rounded or chopped.\n"); + D = FLOOR(Half + POW(Radix, One + Precision - FLOOR(Precision))); + /* ... == Radix^(1 + fract) if (Precision == Integer + fract. */ + X = D / Radix; + Y = D / A1; + if ((X != FLOOR(X)) || (Y != FLOOR(Y))) { + Anomaly = True; + } + else { + X = Zero; + Z2 = X; + Y = One; + Y2 = Y; + Z1 = Radix - One; + FourD = Four * D; + do { + if (Y2 > Z2) { + Q = Radix; + Y1 = Y; + do { + X1 = FABS(Q + FLOOR(Half - Q / Y1) * Y1); + Q = Y1; + Y1 = X1; + } while ( ! (X1 <= Zero)); + if (Q <= One) { + Z2 = Y2; + Z = Y; + } + } + Y = Y + Two; + X = X + Eight; + Y2 = Y2 + X; + if (Y2 >= FourD) Y2 = Y2 - FourD; + } while ( ! (Y >= D)); + X8 = FourD - Z2; + Q = (X8 + Z * Z) / FourD; + X8 = X8 / Eight; + if (Q != FLOOR(Q)) Anomaly = True; + else { + Break = False; + do { + X = Z1 * Z; + X = X - FLOOR(X / Radix) * Radix; + if (X == One) + Break = True; + else + Z1 = Z1 - One; + } while ( ! (Break || (Z1 <= Zero))); + if ((Z1 <= Zero) && (! Break)) Anomaly = True; + else { + if (Z1 > RadixD2) Z1 = Z1 - Radix; + do { + NewD(); + } while ( ! (U2 * D >= F9)); + if (D * Radix - D != W - D) Anomaly = True; + else { + Z2 = D; + I = 0; + Y = D + (One + Z) * Half; + X = D + Z + Q; + SR3750(); + Y = D + (One - Z) * Half + D; + X = D - Z + D; + X = X + Q + X; + SR3750(); + NewD(); + if (D - Z2 != W - Z2) Anomaly = True; + else { + Y = (D - Z2) + (Z2 + (One - Z) * Half); + X = (D - Z2) + (Z2 - Z + Q); + SR3750(); + Y = (One + Z) * Half; + X = Q; + SR3750(); + if (I == 0) Anomaly = True; + } + } + } + } + } + if ((I == 0) || Anomaly) { + BadCond(Failure, "Anomalous arithmetic with Integer < "); + printf("Radix^Precision = %.7e\n", W); + printf(" fails test whether sqrt rounds or chops.\n"); + SqRWrng = True; + } + } + if (! Anomaly) { + if (! ((MinSqEr < Zero) || (MaxSqEr > Zero))) { + RSqrt = Rounded; + printf("Square root appears to be correctly rounded.\n"); + } + else { + if ((MaxSqEr + U2 > U2 - Half) || (MinSqEr > Half) + || (MinSqEr + Radix < Half)) SqRWrng = True; + else { + RSqrt = Chopped; + printf("Square root appears to be chopped.\n"); + } + } + } + if (SqRWrng) { + printf("Square root is neither chopped nor correctly rounded.\n"); + printf("Observed errors run from %.7e ", MinSqEr - Half); + printf("to %.7e ulps.\n", Half + MaxSqEr); + TstCond (Serious, MaxSqEr - MinSqEr < Radix * Radix, + "sqrt gets too many last digits wrong"); + } + /*=============================================*/ + Milestone = 90; + /*=============================================*/ + Pause(); + printf("Testing powers Z^i for small Integers Z and i.\n"); + N = 0; + /* ... test powers of zero. */ + I = 0; + Z = -Zero; + M = 3; + Break = False; + do { + X = One; + SR3980(); + if (I <= 10) { + I = 1023; + SR3980(); + } + if (Z == MinusOne) Break = True; + else { + Z = MinusOne; + /* .. if(-1)^N is invalid, replace MinusOne by One. */ + I = - 4; + } + } while ( ! Break); + PrintIfNPositive(); + N1 = N; + N = 0; + Z = A1; + M = (int)FLOOR(Two * LOG(W) / LOG(A1)); + Break = False; + do { + X = Z; + I = 1; + SR3980(); + if (Z == AInvrse) Break = True; + else Z = AInvrse; + } while ( ! (Break)); + /*=============================================*/ + Milestone = 100; + /*=============================================*/ + /* Powers of Radix have been tested, */ + /* next try a few primes */ + M = NoTrials; + Z = Three; + do { + X = Z; + I = 1; + SR3980(); + do { + Z = Z + Two; + } while ( Three * FLOOR(Z / Three) == Z ); + } while ( Z < Eight * Three ); + if (N > 0) { + printf("Errors like this may invalidate financial calculations\n"); + printf("\tinvolving interest rates.\n"); + } + PrintIfNPositive(); + N += N1; + if (N == 0) printf("... no discrepancies found.\n"); + if (N > 0) Pause(); + else printf("\n"); + /*=============================================*/ + /*SPLIT + } +#include "paranoia.h" +void part6(VOID){ +*/ + Milestone = 110; + /*=============================================*/ + printf("Seeking Underflow thresholds UfThold and E0.\n"); + D = U1; + if (Precision != FLOOR(Precision)) { + D = BInvrse; + X = Precision; + do { + D = D * BInvrse; + X = X - One; + } while ( X > Zero); + } + Y = One; + Z = D; + /* ... D is power of 1/Radix < 1. */ + do { + C = Y; + Y = Z; + Z = Y * Y; + } while ((Y > Z) && (Z + Z > Z)); + Y = C; + Z = Y * D; + do { + C = Y; + Y = Z; + Z = Y * D; + } while ((Y > Z) && (Z + Z > Z)); + if (Radix < Two) HInvrse = Two; + else HInvrse = Radix; + H = One / HInvrse; + /* ... 1/HInvrse == H == Min(1/Radix, 1/2) */ + CInvrse = One / C; + E0 = C; + Z = E0 * H; + /* ...1/Radix^(BIG Integer) << 1 << CInvrse == 1/C */ + do { + Y = E0; + E0 = Z; + Z = E0 * H; + } while ((E0 > Z) && (Z + Z > Z)); + UfThold = E0; + E1 = Zero; + Q = Zero; + E9 = U2; + S = One + E9; + D = C * S; + if (D <= C) { + E9 = Radix * U2; + S = One + E9; + D = C * S; + if (D <= C) { + BadCond(Failure, "multiplication gets too many last digits wrong.\n"); + Underflow = E0; + Y1 = Zero; + PseudoZero = Z; + Pause(); + } + } + else { + Underflow = D; + PseudoZero = Underflow * H; + UfThold = Zero; + do { + Y1 = Underflow; + Underflow = PseudoZero; + if (E1 + E1 <= E1) { + Y2 = Underflow * HInvrse; + E1 = FABS(Y1 - Y2); + Q = Y1; + if ((UfThold == Zero) && (Y1 != Y2)) UfThold = Y1; + } + PseudoZero = PseudoZero * H; + } while ((Underflow > PseudoZero) + && (PseudoZero + PseudoZero > PseudoZero)); + } + /* Comment line 4530 .. 4560 */ + if (PseudoZero != Zero) { + printf("\n"); + Z = PseudoZero; + /* ... Test PseudoZero for "phoney- zero" violates */ + /* ... PseudoZero < Underflow or PseudoZero < PseudoZero + PseudoZero + ... */ + if (PseudoZero <= Zero) { + BadCond(Failure, "Positive expressions can underflow to an\n"); + printf("allegedly negative value\n"); + printf("PseudoZero that prints out as: %g .\n", PseudoZero); + X = - PseudoZero; + if (X <= Zero) { + printf("But -PseudoZero, which should be\n"); + printf("positive, isn't; it prints out as %g .\n", X); + } + } + else { + BadCond(Flaw, "Underflow can stick at an allegedly positive\n"); + printf("value PseudoZero that prints out as %g .\n", PseudoZero); + } + TstPtUf(); + } + /*=============================================*/ + Milestone = 120; + /*=============================================*/ + if (CInvrse * Y > CInvrse * Y1) { + S = H * S; + E0 = Underflow; + } + if (! ((E1 == Zero) || (E1 == E0))) { + BadCond(Defect, ""); + if (E1 < E0) { + printf("Products underflow at a higher"); + printf(" threshold than differences.\n"); + if (PseudoZero == Zero) + E0 = E1; + } + else { + printf("Difference underflows at a higher"); + printf(" threshold than products.\n"); + } + } + printf("Smallest strictly positive number found is E0 = %g .\n", E0); + Z = E0; + TstPtUf(); + Underflow = E0; + if (N == 1) Underflow = Y; + I = 4; + if (E1 == Zero) I = 3; + if (UfThold == Zero) I = I - 2; + UfNGrad = True; + switch (I) { + case 1: + UfThold = Underflow; + if ((CInvrse * Q) != ((CInvrse * Y) * S)) { + UfThold = Y; + BadCond(Failure, "Either accuracy deteriorates as numbers\n"); + printf("approach a threshold = %.17e\n", UfThold);; + printf(" coming down from %.17e\n", C); + printf(" or else multiplication gets too many last digits wrong.\n"); + } + Pause(); + break; + + case 2: + BadCond(Failure, "Underflow confuses Comparison, which alleges that\n"); + printf("Q == Y while denying that |Q - Y| == 0; these values\n"); + printf("print out as Q = %.17e, Y = %.17e .\n", Q, Y2); + printf ("|Q - Y| = %.17e .\n" , FABS(Q - Y2)); + UfThold = Q; + break; + + case 3: + X = X; + break; + + case 4: + if ((Q == UfThold) && (E1 == E0) + && (FABS( UfThold - E1 / E9) <= E1)) { + UfNGrad = False; + printf("Underflow is gradual; it incurs Absolute Error =\n"); + printf("(roundoff in UfThold) < E0.\n"); + Y = E0 * CInvrse; + Y = Y * (OneAndHalf + U2); + X = CInvrse * (One + U2); + Y = Y / X; + IEEE = (Y == E0); + } + } + if (UfNGrad) { + printf("\n"); + sigsave = sigfpe; + if (setjmp(ovfl_buf)) { + printf("Underflow / UfThold failed!\n"); + R = H + H; + } + else R = SQRT(Underflow / UfThold); + sigsave = 0; + if (R <= H) { + Z = R * UfThold; + X = Z * (One + R * H * (One + H)); + } + else { + Z = UfThold; + X = Z * (One + H * H * (One + H)); + } + if (! ((X == Z) || (X - Z != Zero))) { + BadCond(Flaw, ""); + printf("X = %.17e\n\tis not equal to Z = %.17e .\n", X, Z); + Z9 = X - Z; + printf("yet X - Z yields %.17e .\n", Z9); + printf(" Should this NOT signal Underflow, "); + printf("this is a SERIOUS DEFECT\nthat causes "); + printf("confusion when innocent statements like\n");; + printf(" if (X == Z) ... else"); + printf(" ... (f(X) - f(Z)) / (X - Z) ...\n"); + printf("encounter Division by Zero although actually\n"); + sigsave = sigfpe; + if (setjmp(ovfl_buf)) printf("X / Z fails!\n"); + else printf("X / Z = 1 + %g .\n", (X / Z - Half) - Half); + sigsave = 0; + } + } + printf("The Underflow threshold is %.17e, %s\n", UfThold, + " below which"); + printf("calculation may suffer larger Relative error than "); + printf("merely roundoff.\n"); + Y2 = U1 * U1; + Y = Y2 * Y2; + Y2 = Y * U1; + if (Y2 <= UfThold) { + if (Y > E0) { + BadCond(Defect, ""); + I = 5; + } + else { + BadCond(Serious, ""); + I = 4; + } + printf("Range is too narrow; U1^%d Underflows.\n", I); + } + /*=============================================*/ + /*SPLIT + } +#include "paranoia.h" +void part7(VOID){ +*/ + Milestone = 130; + /*=============================================*/ + Y = - FLOOR(Half - TwoForty * LOG(UfThold) / LOG(HInvrse)) / TwoForty; + Y2 = Y + Y; + printf("Since underflow occurs below the threshold\n"); + printf("UfThold = (%.17e) ^ (%.17e)\nonly underflow ", HInvrse, Y); + printf("should afflict the expression\n\t(%.17e) ^ (%.17e);\n", + HInvrse, Y2); + printf("actually calculating yields:"); + if (setjmp(ovfl_buf)) { + sigsave = 0; + BadCond(Serious, "trap on underflow.\n"); + } + else { + sigsave = sigfpe; + V9 = POW(HInvrse, Y2); + sigsave = 0; + printf(" %.17e .\n", V9); + if (! ((V9 >= Zero) && (V9 <= (Radix + Radix + E9) * UfThold))) { + BadCond(Serious, "this is not between 0 and underflow\n"); + printf(" threshold = %.17e .\n", UfThold); + } + else if (! (V9 > UfThold * (One + E9))) + printf("This computed value is O.K.\n"); + else { + BadCond(Defect, "this is not between 0 and underflow\n"); + printf(" threshold = %.17e .\n", UfThold); + } + } + /*=============================================*/ + Milestone = 140; + /*=============================================*/ + printf("\n"); + /* ...calculate Exp2 == exp(2) == 7.389056099... */ + X = Zero; + I = 2; + Y = Two * Three; + Q = Zero; + N = 0; + do { + Z = X; + I = I + 1; + Y = Y / (I + I); + R = Y + Q; + X = Z + R; + Q = (Z - X) + R; + } while(X > Z); + Z = (OneAndHalf + One / Eight) + X / (OneAndHalf * ThirtyTwo); + X = Z * Z; + Exp2 = X * X; + X = F9; + Y = X - U1; + printf("Testing X^((X + 1) / (X - 1)) vs. exp(2) = %.17e as X -> 1.\n", + Exp2); + for(I = 1;;) { + Z = X - BInvrse; + Z = (X + One) / (Z - (One - BInvrse)); + Q = POW(X, Z) - Exp2; + if (FABS(Q) > TwoForty * U2) { + N = 1; + V9 = (X - BInvrse) - (One - BInvrse); + BadCond(Defect, "Calculated"); + printf(" %.17e for\n", POW(X,Z)); + printf("\t(1 + (%.17e) ^ (%.17e);\n", V9, Z); + printf("\tdiffers from correct value by %.17e .\n", Q); + printf("\tThis much error may spoil financial\n"); + printf("\tcalculations involving tiny interest rates.\n"); + break; + } + else { + Z = (Y - X) * Two + Y; + X = Y; + Y = Z; + Z = One + (X - F9)*(X - F9); + if (Z > One && I < NoTrials) I++; + else { + if (X > One) { + if (N == 0) + printf("Accuracy seems adequate.\n"); + break; + } + else { + X = One + U2; + Y = U2 + U2; + Y += X; + I = 1; + } + } + } + } + /*=============================================*/ + Milestone = 150; + /*=============================================*/ + printf("Testing powers Z^Q at four nearly extreme values.\n"); + N = 0; + Z = A1; + Q = FLOOR(Half - LOG(C) / LOG(A1)); + Break = False; + do { + X = CInvrse; + Y = POW(Z, Q); + IsYeqX(); + Q = - Q; + X = C; + Y = POW(Z, Q); + IsYeqX(); + if (Z < One) Break = True; + else Z = AInvrse; + } while ( ! (Break)); + PrintIfNPositive(); + if (N == 0) printf(" ... no discrepancies found.\n"); + printf("\n"); + + /*=============================================*/ + Milestone = 160; + /*=============================================*/ + Pause(); + printf("Searching for Overflow threshold:\n"); + printf("This may generate an error.\n"); + Y = - CInvrse; + V9 = HInvrse * Y; + sigsave = sigfpe; + if (setjmp(ovfl_buf)) { I = 0; V9 = Y; goto overflow; } + do { + V = Y; + Y = V9; + V9 = HInvrse * Y; + } while(V9 < Y); + I = 1; +overflow: + sigsave = 0; + Z = V9; + printf("Can `Z = -Y' overflow?\n"); + printf("Trying it on Y = %.17e .\n", Y); + V9 = - Y; + V0 = V9; + if (V - Y == V + V0) printf("Seems O.K.\n"); + else { + printf("finds a "); + BadCond(Flaw, "-(-Y) differs from Y.\n"); + } + if (Z != Y) { + BadCond(Serious, ""); + printf("overflow past %.17e\n\tshrinks to %.17e .\n", Y, Z); + } + if (I) { + Y = V * (HInvrse * U2 - HInvrse); + Z = Y + ((One - HInvrse) * U2) * V; + if (Z < V0) Y = Z; + if (Y < V0) V = Y; + if (V0 - V < V0) V = V0; + } + else { + V = Y * (HInvrse * U2 - HInvrse); + V = V + ((One - HInvrse) * U2) * Y; + } + printf("Overflow threshold is V = %.17e .\n", V); + if (I) printf("Overflow saturates at V0 = %.17e .\n", V0); + else printf("There is no saturation value because \ +the system traps on overflow.\n"); + V9 = V * One; + printf("No Overflow should be signaled for V * 1 = %.17e\n", V9); + V9 = V / One; + printf(" nor for V / 1 = %.17e .\n", V9); + printf("Any overflow signal separating this * from the one\n"); + printf("above is a DEFECT.\n"); + /*=============================================*/ + Milestone = 170; + /*=============================================*/ + if (!(-V < V && -V0 < V0 && -UfThold < V && UfThold < V)) { + BadCond(Failure, "Comparisons involving "); + printf("+-%g, +-%g\nand +-%g are confused by Overflow.", + V, V0, UfThold); + } + /*=============================================*/ + Milestone = 175; + /*=============================================*/ + printf("\n"); + for(Indx = 1; Indx <= 3; ++Indx) { + switch (Indx) { + case 1: Z = UfThold; break; + case 2: Z = E0; break; + case 3: Z = PseudoZero; break; + } + if (Z != Zero) { + V9 = SQRT(Z); + Y = V9 * V9; + if (Y / (One - Radix * E9) < Z + || Y > (One + Radix * E9) * Z) { /* dgh: + E9 --> * E9 */ + if (V9 > U1) BadCond(Serious, ""); + else BadCond(Defect, ""); + printf("Comparison alleges that what prints as Z = %.17e\n", Z); + printf(" is too far from sqrt(Z) ^ 2 = %.17e .\n", Y); + } + } + } + /*=============================================*/ + Milestone = 180; + /*=============================================*/ + for(Indx = 1; Indx <= 2; ++Indx) { + if (Indx == 1) Z = V; + else Z = V0; + V9 = SQRT(Z); + X = (One - Radix * E9) * V9; + V9 = V9 * X; + if (((V9 < (One - Two * Radix * E9) * Z) || (V9 > Z))) { + Y = V9; + if (X < W) BadCond(Serious, ""); + else BadCond(Defect, ""); + printf("Comparison alleges that Z = %17e\n", Z); + printf(" is too far from sqrt(Z) ^ 2 (%.17e) .\n", Y); + } + } + /*=============================================*/ + /*SPLIT + } +#include "paranoia.h" +int part8(VOID){ +*/ + Milestone = 190; + /*=============================================*/ + Pause(); + X = UfThold * V; + Y = Radix * Radix; + if (X*Y < One || X > Y) { + if (X * Y < U1 || X > Y/U1) BadCond(Defect, "Badly"); + else BadCond(Flaw, ""); + + printf(" unbalanced range; UfThold * V = %.17e\n\t%s\n", + X, "is too far from 1.\n"); + } + /*=============================================*/ + Milestone = 200; + /*=============================================*/ + for (Indx = 1; Indx <= 5; ++Indx) { + X = F9; + switch (Indx) { + case 2: X = One + U2; break; + case 3: X = V; break; + case 4: X = UfThold; break; + case 5: X = Radix; + } + Y = X; + sigsave = sigfpe; + if (setjmp(ovfl_buf)) + printf(" X / X traps when X = %g\n", X); + else { + V9 = (Y / X - Half) - Half; + if (V9 == Zero) continue; + if (V9 == - U1 && Indx < 5) BadCond(Flaw, ""); + else BadCond(Serious, ""); + printf(" X / X differs from 1 when X = %.17e\n", X); + printf(" instead, X / X - 1/2 - 1/2 = %.17e .\n", V9); + } + sigsave = 0; + } + /*=============================================*/ + Milestone = 210; + /*=============================================*/ + MyZero = Zero; + printf("\n"); + printf("What message and/or values does Division by Zero produce?\n") ; +#ifndef NOPAUSE + printf("This can interupt your program. You can "); + printf("skip this part if you wish.\n"); + printf("Do you wish to compute 1 / 0? "); + fflush(stdout); + read (KEYBOARD, ch, 8); + if ((ch[0] == 'Y') || (ch[0] == 'y')) { +#endif + sigsave = sigfpe; + printf(" Trying to compute 1 / 0 produces ..."); + if (!setjmp(ovfl_buf)) printf(" %.7e .\n", One / MyZero); + sigsave = 0; +#ifndef NOPAUSE + } + else printf("O.K.\n"); + printf("\nDo you wish to compute 0 / 0? "); + fflush(stdout); + read (KEYBOARD, ch, 80); + if ((ch[0] == 'Y') || (ch[0] == 'y')) { +#endif + sigsave = sigfpe; + printf("\n Trying to compute 0 / 0 produces ..."); + if (!setjmp(ovfl_buf)) printf(" %.7e .\n", Zero / MyZero); + sigsave = 0; +#ifndef NOPAUSE + } + else printf("O.K.\n"); +#endif + /*=============================================*/ + Milestone = 220; + /*=============================================*/ + Pause(); + printf("\n"); + { + static char *msg[] = { + "FAILUREs encountered =", + "SERIOUS DEFECTs discovered =", + "DEFECTs discovered =", + "FLAWs discovered =" }; + int i; + for(i = 0; i < 4; i++) if (ErrCnt[i]) + printf("The number of %-29s %d.\n", + msg[i], ErrCnt[i]); + } + printf("\n"); + if ((ErrCnt[Failure] + ErrCnt[Serious] + ErrCnt[Defect] + + ErrCnt[Flaw]) > 0) { + if ((ErrCnt[Failure] + ErrCnt[Serious] + ErrCnt[ + Defect] == 0) && (ErrCnt[Flaw] > 0)) { + printf("The arithmetic diagnosed seems "); + printf("Satisfactory though flawed.\n"); + } + if ((ErrCnt[Failure] + ErrCnt[Serious] == 0) + && ( ErrCnt[Defect] > 0)) { + printf("The arithmetic diagnosed may be Acceptable\n"); + printf("despite inconvenient Defects.\n"); + } + if ((ErrCnt[Failure] + ErrCnt[Serious]) > 0) { + printf("The arithmetic diagnosed has "); + printf("unacceptable Serious Defects.\n"); + } + if (ErrCnt[Failure] > 0) { + printf("Potentially fatal FAILURE may have spoiled this"); + printf(" program's subsequent diagnoses.\n"); + } + } + else { + printf("No failures, defects nor flaws have been discovered.\n"); + if (! ((RMult == Rounded) && (RDiv == Rounded) + && (RAddSub == Rounded) && (RSqrt == Rounded))) + printf("The arithmetic diagnosed seems Satisfactory.\n"); + else { + if (StickyBit >= One && + (Radix - Two) * (Radix - Nine - One) == Zero) { + printf("Rounding appears to conform to "); + printf("the proposed IEEE standard P"); + if ((Radix == Two) && + ((Precision - Four * Three * Two) * + ( Precision - TwentySeven - + TwentySeven + One) == Zero)) + printf("754"); + else printf("854"); + if (IEEE) printf(".\n"); + else { + printf(",\nexcept for possibly Double Rounding"); + printf(" during Gradual Underflow.\n"); + } + } + printf("The arithmetic diagnosed appears to be Excellent!\n"); + } + } + if (fpecount) + printf("\nA total of %d floating point exceptions were registered.\n", + fpecount); + printf("END OF TEST.\n"); + return 0; + } + +/*SPLIT subs.c +#include "paranoia.h" +*/ + + FLOAT +Sign (FP X) +#ifdef KR_headers +FLOAT X; +#endif +{ return X >= 0. ? 1.0 : -1.0; } + + void +Pause(VOID) +{ +#ifndef NOPAUSE + char ch[8]; + + printf("\nTo continue, press RETURN"); + fflush(stdout); + read(KEYBOARD, ch, 8); +#endif + printf("\nDiagnosis resumes after milestone Number %d", Milestone); + printf(" Page: %d\n\n", PageNo); + ++Milestone; + ++PageNo; + } + + void +TstCond (INT K, INT Valid, CHARP T) +#ifdef KR_headers +int K, Valid; +char *T; +#endif +{ if (! Valid) { BadCond(K,T); printf(".\n"); } } + + void +BadCond(INT K, CHARP T) +#ifdef KR_headers +int K; +char *T; +#endif +{ + static char *msg[] = { "FAILURE", "SERIOUS DEFECT", "DEFECT", "FLAW" }; + + ErrCnt [K] = ErrCnt [K] + 1; + printf("%s: %s", msg[K], T); + } + + + FLOAT +Random(VOID) +/* Random computes + X = (Random1 + Random9)^5 + Random1 = X - FLOOR(X) + 0.000005 * X; + and returns the new value of Random1 +*/ +{ + FLOAT X, Y; + + X = Random1 + Random9; + Y = X * X; + Y = Y * Y; + X = X * Y; + Y = X - FLOOR(X); + Random1 = Y + X * 0.000005; + return(Random1); + } + + void +SqXMinX (INT ErrKind) +#ifdef KR_headers +int ErrKind; +#endif +{ + FLOAT XA, XB; + + XB = X * BInvrse; + XA = X - XB; + SqEr = ((SQRT(X * X) - XB) - XA) / OneUlp; + if (SqEr != Zero) { + if (SqEr < MinSqEr) MinSqEr = SqEr; + if (SqEr > MaxSqEr) MaxSqEr = SqEr; + J = J + 1.0; + BadCond(ErrKind, "\n"); + printf("sqrt( %.17e) - %.17e = %.17e\n", X * X, X, OneUlp * SqEr); + printf("\tinstead of correct value 0 .\n"); + } + } + + void +NewD(VOID) +{ + X = Z1 * Q; + X = FLOOR(Half - X / Radix) * Radix + X; + Q = (Q - X * Z) / Radix + X * X * (D / Radix); + Z = Z - Two * X * D; + if (Z <= Zero) { + Z = - Z; + Z1 = - Z1; + } + D = Radix * D; + } + + void +SR3750(VOID) +{ + if (! ((X - Radix < Z2 - Radix) || (X - Z2 > W - Z2))) { + I = I + 1; + X2 = SQRT(X * D); + Y2 = (X2 - Z2) - (Y - Z2); + X2 = X8 / (Y - Half); + X2 = X2 - Half * X2 * X2; + SqEr = (Y2 + Half) + (Half - X2); + if (SqEr < MinSqEr) MinSqEr = SqEr; + SqEr = Y2 - X2; + if (SqEr > MaxSqEr) MaxSqEr = SqEr; + } + } + + void +IsYeqX(VOID) +{ + if (Y != X) { + if (N <= 0) { + if (Z == Zero && Q <= Zero) + printf("WARNING: computing\n"); + else BadCond(Defect, "computing\n"); + printf("\t(%.17e) ^ (%.17e)\n", Z, Q); + printf("\tyielded %.17e;\n", Y); + printf("\twhich compared unequal to correct %.17e ;\n", + X); + printf("\t\tthey differ by %.17e .\n", Y - X); + } + N = N + 1; /* ... count discrepancies. */ + } + } + + void +SR3980(VOID) +{ + do { + Q = (FLOAT) I; + Y = POW(Z, Q); + IsYeqX(); + if (++I > M) break; + X = Z * X; + } while ( X < W ); + } + + void +PrintIfNPositive(VOID) +{ + if (N > 0) printf("Similar discrepancies have occurred %d times.\n", N); + } + + void +TstPtUf(VOID) +{ + N = 0; + if (Z != Zero) { + printf("Since comparison denies Z = 0, evaluating "); + printf("(Z + Z) / Z should be safe.\n"); + sigsave = sigfpe; + if (setjmp(ovfl_buf)) goto very_serious; + Q9 = (Z + Z) / Z; + printf("What the machine gets for (Z + Z) / Z is %.17e .\n", + Q9); + if (FABS(Q9 - Two) < Radix * U2) { + printf("This is O.K., provided Over/Underflow"); + printf(" has NOT just been signaled.\n"); + } + else { + if ((Q9 < One) || (Q9 > Two)) { +very_serious: + N = 1; + ErrCnt [Serious] = ErrCnt [Serious] + 1; + printf("This is a VERY SERIOUS DEFECT!\n"); + } + else { + N = 1; + ErrCnt [Defect] = ErrCnt [Defect] + 1; + printf("This is a DEFECT!\n"); + } + } + sigsave = 0; + V9 = Z * One; + Random1 = V9; + V9 = One * Z; + Random2 = V9; + V9 = Z / One; + if ((Z == Random1) && (Z == Random2) && (Z == V9)) { + if (N > 0) Pause(); + } + else { + N = 1; + BadCond(Defect, "What prints as Z = "); + printf("%.17e\n\tcompares different from ", Z); + if (Z != Random1) printf("Z * 1 = %.17e ", Random1); + if (! ((Z == Random2) + || (Random2 == Random1))) + printf("1 * Z == %g\n", Random2); + if (! (Z == V9)) printf("Z / 1 = %.17e\n", V9); + if (Random2 != Random1) { + ErrCnt [Defect] = ErrCnt [Defect] + 1; + BadCond(Defect, "Multiplication does not commute!\n"); + printf("\tComparison alleges that 1 * Z = %.17e\n", + Random2); + printf("\tdiffers from Z * 1 = %.17e\n", Random1); + } + Pause(); + } + } + } + + void +notify(CHARP s) +#ifdef KR_headers + char *s; +#endif +{ + printf("%s test appears to be inconsistent...\n", s); + printf(" PLEASE NOTIFY KARPINKSI!\n"); + } + +/*SPLIT msgs.c +#include "paranoia.h" +*/ + + void +msglist(CHARPP s) +#ifdef KR_headers +char **s; +#endif +{ while(*s) printf("%s\n", *s++); } + + void +Instructions(VOID) +{ + static char *instr[] = { + "Lest this program stop prematurely, i.e. before displaying\n", + " `END OF TEST',\n", + "try to persuade the computer NOT to terminate execution when an", + "error like Over/Underflow or Division by Zero occurs, but rather", + "to persevere with a surrogate value after, perhaps, displaying some", + "warning. If persuasion avails naught, don't despair but run this", + "program anyway to see how many milestones it passes, and then", + "amend it to make further progress.\n", + "Answer questions with Y, y, N or n (unless otherwise indicated).\n", + 0}; + + msglist(instr); + } + + void +Heading(VOID) +{ + static char *head[] = { + "Users are invited to help debug and augment this program so it will", + "cope with unanticipated and newly uncovered arithmetic pathologies.\n", + "Please send suggestions and interesting results to", + "\tRichard Karpinski", + "\tComputer Center U-76", + "\tUniversity of California", + "\tSan Francisco, CA 94143-0704, USA\n", + "In doing so, please include the following information:", +#ifdef Single + "\tPrecision:\tsingle;", +#else + "\tPrecision:\tdouble;", +#endif + "\tVersion:\t10 February 1989;", + "\tComputer:\n", + "\tCompiler:\n", + "\tOptimization level:\n", + "\tOther relevant compiler options:", + 0}; + + msglist(head); + } + + void +Characteristics(VOID) +{ + static char *chars[] = { + "Running this program should reveal these characteristics:", + " Radix = 1, 2, 4, 8, 10, 16, 100, 256 ...", + " Precision = number of significant digits carried.", + " U2 = Radix/Radix^Precision = One Ulp", + "\t(OneUlpnit in the Last Place) of 1.000xxx .", + " U1 = 1/Radix^Precision = One Ulp of numbers a little less than 1.0 .", + " Adequacy of guard digits for Mult., Div. and Subt.", + " Whether arithmetic is chopped, correctly rounded, or something else", + "\tfor Mult., Div., Add/Subt. and Sqrt.", + " Whether a Sticky Bit used correctly for rounding.", + " UnderflowThreshold = an underflow threshold.", + " E0 and PseudoZero tell whether underflow is abrupt, gradual, or fuzzy.", + " V = an overflow threshold, roughly.", + " V0 tells, roughly, whether Infinity is represented.", + " Comparisions are checked for consistency with subtraction", + "\tand for contamination with pseudo-zeros.", + " Sqrt is tested. Y^X is not tested.", + " Extra-precise subexpressions are revealed but NOT YET tested.", + " Decimal-Binary conversion is NOT YET tested for accuracy.", + 0}; + + msglist(chars); + } + + void +History(VOID) +{ /* History */ + /* Converted from Brian Wichmann's Pascal version to C by Thos Sumner, + with further massaging by David M. Gay. */ + + static char *hist[] = { + "The program attempts to discriminate among", + " FLAWs, like lack of a sticky bit,", + " Serious DEFECTs, like lack of a guard digit, and", + " FAILUREs, like 2+2 == 5 .", + "Failures may confound subsequent diagnoses.\n", + "The diagnostic capabilities of this program go beyond an earlier", + "program called `MACHAR', which can be found at the end of the", + "book `Software Manual for the Elementary Functions' (1980) by", + "W. J. Cody and W. Waite. Although both programs try to discover", + "the Radix, Precision and range (over/underflow thresholds)", + "of the arithmetic, this program tries to cope with a wider variety", + "of pathologies, and to say how well the arithmetic is implemented.", + "\nThe program is based upon a conventional radix representation for", + "floating-point numbers, but also allows logarithmic encoding", + "as used by certain early WANG machines.\n", + "BASIC version of this program (C) 1983 by Prof. W. M. Kahan;", + "see source comments for more history.", + 0}; + + msglist(hist); + }