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hack to speed up conversion to decimal with huge numbers

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This commit is contained in:
Fredrik Johansson 2016-03-06 19:16:41 +01:00
parent 11a26572a4
commit d3f69b7aca
1 changed files with 21 additions and 4 deletions
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25
arb/get_fmpz_mid_rad_10exp.c
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@ -25,6 +25,25 @@
#include "arb.h" #include "arb.h"
/* todo: make arb_pow_fmpz automatic */
void
_arb_10_pow_fmpz(arb_t res, const fmpz_t m, slong prec)
{
slong bits = fmpz_bits(m);
if (bits < 128)
{
arb_set_ui(res, 10);
arb_pow_fmpz_binexp(res, res, m, prec + 2 * bits);
}
else
{
arb_const_log10(res, prec + bits);
arb_mul_fmpz(res, res, m, prec + bits);
arb_exp(res, res, prec + bits);
}
}
void void
arb_get_fmpz_mid_rad_10exp(fmpz_t mid, fmpz_t rad, fmpz_t exp, const arb_t x, slong n) arb_get_fmpz_mid_rad_10exp(fmpz_t mid, fmpz_t rad, fmpz_t exp, const arb_t x, slong n)
{ {
@ -68,21 +87,19 @@ arb_get_fmpz_mid_rad_10exp(fmpz_t mid, fmpz_t rad, fmpz_t exp, const arb_t x, sl
arf_get_fmpz(m, arb_midref(t), ARF_RND_FLOOR); arf_get_fmpz(m, arb_midref(t), ARF_RND_FLOOR);
arb_set_ui(t, 10);
fmpz_neg(exp, m); fmpz_neg(exp, m);
prec = n * 3.32192809488736 + 30; prec = n * 3.32192809488736 + 30;
if (fmpz_sgn(m) >= 0) if (fmpz_sgn(m) >= 0)
{ {
arb_pow_fmpz_binexp(t, t, m, prec + 2 * fmpz_bits(m)); _arb_10_pow_fmpz(t, m, prec);
arb_mul(t, x, t, prec); arb_mul(t, x, t, prec);
} }
else else
{ {
fmpz_neg(m, m); fmpz_neg(m, m);
arb_pow_fmpz_binexp(t, t, m, prec + 2 * fmpz_bits(m)); _arb_10_pow_fmpz(t, m, prec);
arb_div(t, x, t, prec); arb_div(t, x, t, prec);
} }