mirror of
https://github.com/vale981/arb
synced 2025-03-05 09:21:38 -05:00
6bf072eb59
This will allow us to not loose the julia session on error. See also https://github.com/wbhart/flint2/pull/243
62 lines
1.3 KiB
C
62 lines
1.3 KiB
C
/*
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Copyright (C) 2012 Fredrik Johansson
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This file is part of Arb.
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Arb is free software: you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version. See <http://www.gnu.org/licenses/>.
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*/
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#include <math.h>
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#include "flint/double_extras.h"
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#include "hypgeom.h"
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#define LOG2 0.69314718055994530942
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#define EXP1 2.7182818284590452354
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static __inline__ double d_root(double x, int r)
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{
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if (r == 1)
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return x;
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if (r == 2)
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return sqrt(x);
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return pow(x, 1. / r);
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}
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slong
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hypgeom_estimate_terms(const mag_t z, int r, slong prec)
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{
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double y, t;
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t = mag_get_d(z);
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if (t == 0)
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return 1;
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if (r == 0)
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{
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if (t >= 1)
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{
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flint_printf("z must be smaller than 1\n");
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flint_abort();
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}
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y = (log(1-t) - prec * LOG2) / log(t) + 1;
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}
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else
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{
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y = (prec * LOG2) / (d_root(t, r) * EXP1 * r);
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y = (prec * LOG2) / (r * d_lambertw(y)) + 1;
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}
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if (y >= WORD_MAX / 2)
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{
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flint_printf("error: series will converge too slowly\n");
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flint_abort();
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}
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return y;
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}
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