mirror of
https://github.com/vale981/arb
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102 lines
3.1 KiB
C
102 lines
3.1 KiB
C
/*=============================================================================
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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
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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ARB is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with ARB; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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=============================================================================*/
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/******************************************************************************
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Copyright (C) 2012, 2013 Fredrik Johansson
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******************************************************************************/
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#include "fmprb.h"
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void
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_fmprb_pow_exp(fmprb_t z, const fmprb_t x, const fmprb_t y, long prec)
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{
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fmprb_t t;
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fmprb_init(t);
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fmprb_log(t, x, prec);
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fmprb_mul(t, t, y, prec);
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fmprb_exp(z, t, prec);
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fmprb_clear(t);
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}
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void
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fmprb_pow(fmprb_t z, const fmprb_t x, const fmprb_t y, long prec)
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{
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if (fmprb_is_exact(y))
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{
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if (fmpr_is_zero(fmprb_midref(y)))
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{
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fmprb_one(z);
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return;
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}
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if (!fmpr_is_special(fmprb_midref(y)) && !fmpr_is_special(fmprb_midref(x)))
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{
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const fmpz * exp_exp = fmpr_expref(fmprb_midref(y));
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/* smallish integer powers and square roots */
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if (!COEFF_IS_MPZ(*exp_exp) && (*exp_exp >= -1L))
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{
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long exp_bits;
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exp_bits = *exp_exp + fmpz_bits(fmpr_manref(fmprb_midref(y)));
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if (exp_bits < 64)
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{
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fmpz_t e;
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fmpz_init(e);
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if (*exp_exp == -1L)
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{
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fmprb_sqrt(z, x, prec + exp_bits);
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fmpz_set(e, fmpr_manref(fmprb_midref(y)));
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fmprb_pow_fmpz_binexp(z, z, e, prec);
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}
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else
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{
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fmpz_mul_2exp(e, fmpr_manref(fmprb_midref(y)), *exp_exp);
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fmprb_pow_fmpz_binexp(z, x, e, prec);
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}
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fmpz_clear(e);
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return;
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}
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}
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/* (-x)^n = (-1)^n * x^n */
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if (fmpz_sgn(exp_exp) >= 0 && fmpr_sgn(fmprb_midref(x)) < 0)
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{
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fmprb_t t;
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int odd;
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fmprb_init(t);
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fmprb_neg(t, x);
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odd = fmpz_is_zero(exp_exp);
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_fmprb_pow_exp(z, t, y, prec);
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if (odd)
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fmprb_neg(z, z);
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fmprb_clear(t);
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return;
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}
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}
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}
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_fmprb_pow_exp(z, x, y, prec);
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}
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