Tester based on Handbook of Floating-Point Arithmetic 1.1

[ipdf/code.git] / src / tests / handbook1-1.cpp

diff --git a/src/tests/handbook1-1.cpp b/src/tests/handbook1-1.cpp
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+/**
+ * From Handbook of Floating-Point Arithmetic
+ * Program 1.1 "A sequence that seems to converge to a wrong limit"
+ * Modified to work with a template type and then print the results for our favourite types
+ * I know it is O(N^2) when it should be O(N), but in terms of amount of typing it is O(much nicer this way for small values of N)
+ */
+
+#include <cstdio>
+#include "real.h"
+
+using namespace std;
+using namespace IPDF;
+
+template <class T> T s(T u, T v, int max)
+{
+       T w = 0.;
+       for (int i = 3; i <= max; i++)
+       {
+               w = T(111.) - T(1130.)/v + T(3000.)/(v*u);
+               u = v;
+               v = w;
+       }
+       return w;
+}
+
+int main(void)
+{
+       double u0 = 2;
+       double u1 = -4;
+       printf("#n\tfloat\tdouble\tlong\tReal\n");
+       for (int i = 3; i <= 30; ++i)
+       {
+               printf("%d\t%.15f\t%.15lf\t%.15llf\t%.15lf\n", i,
+                       s<float>(u0,u1,i), s<double>(u0,u1,i), s<long double>(u0,u1,i), Float(s<Real>(u0,u1,i)));
+       }
+
+       return 0;
+}