# source:trunk/test/math/pi.cpp@1010Tweet

Last change on this file since 1010 was 1008, checked in by sam, 11 years ago

test: add missing <cstdio> include in pi test program.

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File size: 1.3 KB
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1//
2// Lol Engine - Sample math program: compute Pi
3//
4// Copyright: (c) 2005-2011 Sam Hocevar <sam@hocevar.net>
5//   This program is free software; you can redistribute it and/or
6//   modify it under the terms of the Do What The Fuck You Want To
8//   http://sam.zoy.org/projects/COPYING.WTFPL for more details.
9//
10
11#if defined HAVE_CONFIG_H
12#   include "config.h"
13#endif
14
15#include <cstdio>
16
17#include "core.h"
18
19using namespace lol;
20using namespace std;
21
22int main(int argc, char **argv)
23{
24    printf("Pi: "); real::R_PI.print();
25    printf("e: "); real::R_E.print();
26    printf("ln(2): "); real::R_LN2.print();
27    printf("sqrt(2): "); real::R_SQRT2.print();
28    printf("sqrt(1/2): "); real::R_SQRT1_2.print();
29
30    /* Gauss-Legendre computation of Pi -- doesn't work well at all,
31     * probably because we use finite precision. */
32    real a = 1.0, b = sqrt((real)0.5), t = 0.25, p = 1.0;
33
34    for (int i = 0; i < 3; i++)
35    {
36        real a2 = (a + b) * (real)0.5;
37        real b2 = sqrt(a * b);
38        real tmp = a - a2;
39        real t2 = t - p * tmp * tmp;
40        real p2 = p + p;
41        a = a2; b = b2; t = t2; p = p2;
42    }
43
44    real sum = a + b;
45    sum = sum * sum / ((real)4 * t);
46    sum.print();
47
48    return EXIT_SUCCESS;
49}
50
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