From d3f69b7acae43ddcd31ae23b6ff33fa6e77503d5 Mon Sep 17 00:00:00 2001 From: Fredrik Johansson Date: Sun, 6 Mar 2016 19:16:41 +0100 Subject: [PATCH] hack to speed up conversion to decimal with huge numbers --- arb/get_fmpz_mid_rad_10exp.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/arb/get_fmpz_mid_rad_10exp.c b/arb/get_fmpz_mid_rad_10exp.c index dbf96cbb..a4a32bef 100644 --- a/arb/get_fmpz_mid_rad_10exp.c +++ b/arb/get_fmpz_mid_rad_10exp.c @@ -25,6 +25,25 @@ #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 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); - arb_set_ui(t, 10); - fmpz_neg(exp, m); prec = n * 3.32192809488736 + 30; 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); } else { 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); }