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49 lines
1.3 KiB
Plaintext
49 lines
1.3 KiB
Plaintext
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/** \page gncnumericexample gnc_numeric Example
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\section example EXAMPLE
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The following program finds the best ::gnc_numeric approximation to
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the \a math.h constant \a M_PI given a maximum denominator. For
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large denominators, the ::gnc_numeric approximation is accurate to
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more decimal places than will generally be needed, but in some cases
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this may not be good enough. For example,
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@verbatim
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M_PI = 3.14159265358979323846
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245850922 / 78256779 = 3.14159265358979311599 (16 sig figs)
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3126535 / 995207 = 3.14159265358865047446 (12 sig figs)
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355 / 113 = 3.14159292035398252096 (7 sig figs)
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@endverbatim
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@verbatim
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#include <glib.h>
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#include <qof.h>
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#include <math.h>
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int
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main(int argc, char ** argv)
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{
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gnc_numeric approx, best;
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double err, best_err=1.0;
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double m_pi = M_PI;
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gint64 denom;
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gint64 max;
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sscanf(argv[1], "%Ld", &max);
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for (denom = 1; denom < max; denom++)
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{
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approx = double_to_gnc_numeric (m_pi, denom, GNC_RND_ROUND);
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err = m_pi - gnc_numeric_to_double (approx);
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if (fabs (err) < fabs (best_err))
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{
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best = approx;
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best_err = err;
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printf ("%Ld / %Ld = %.30f\n", gnc_numeric_num (best),
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gnc_numeric_denom (best), gnc_numeric_to_double (best));
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}
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}
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}
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@endverbatim
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*/
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