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port the div_2expm1_ui code completely to the arb type

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This commit is contained in:
Fredrik Johansson 2015-07-21 18:05:30 +02:00
parent b24d5d482d
commit 6c81cba454
6 changed files with 50 additions and 172 deletions
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61
fmprb/div_2expm1.c → arb/div_2expm1_ui.c
View file

@ -19,61 +19,64 @@
=============================================================================*/
/******************************************************************************
Copyright (C) 2012 Fredrik Johansson
Copyright (C) 2015 Fredrik Johansson
******************************************************************************/
#include "fmprb.h"
#include "arb.h"
/* TODO: fix/optimize for n > prec */
void
fmprb_div_2expm1_ui(fmprb_t y, const fmprb_t x, ulong n, long prec)
arb_div_2expm1_ui(arb_t y, const arb_t x, ulong n, long prec)
{
if (n < FLINT_BITS)
{
fmprb_div_ui(y, x, (1UL << n) - 1, prec);
arb_div_ui(y, x, (1UL << n) - 1, prec);
}
else if (n < 1024 + prec / 32 || n > LONG_MAX / 2)
else if (n < 1024 + prec / 32 || n > LONG_MAX / 4)
{
fmprb_t t;
fmprb_init(t);
fmprb_one(t);
fmpz_set_ui(fmpr_expref(fmprb_midref(t)), n);
fmprb_sub_ui(t, t, 1, prec);
fmprb_div(y, x, t, prec);
fmprb_clear(t);
arb_t t;
fmpz_t e;
arb_init(t);
fmpz_init_set_ui(e, n);
arb_one(t);
arb_mul_2exp_fmpz(t, t, e);
arb_sub_ui(t, t, 1, prec);
arb_div(y, x, t, prec);
arb_clear(t);
fmpz_clear(e);
}
else
{
fmprb_t s, t;
arb_t s, t;
long i, b;
fmprb_init(s);
fmprb_init(t);
arb_init(s);
arb_init(t);
/* x / (2^n - 1) = sum_{k>=1} x * 2^(-k*n)*/
fmprb_mul_2exp_si(s, x, -n);
fmprb_set(t, s);
arb_mul_2exp_si(s, x, -n);
arb_set(t, s);
b = 1;
for (i = 2; i <= prec / n + 1; i++)
{
fmprb_mul_2exp_si(t, t, -n);
fmprb_add(s, s, t, prec);
arb_mul_2exp_si(t, t, -n);
arb_add(s, s, t, prec);
b = i;
}
/* error bound: sum_{k>b} x * 2^(-k*n) <= x * 2^(-b*n - (n-1)) */
fmprb_mul_2exp_si(t, x, -b*n - (n-1));
fmprb_abs(t, t);
fmprb_add_error(s, t);
arb_mul_2exp_si(t, x, -b*n - (n-1));
arb_abs(t, t);
arb_add_error(s, t);
fmprb_set(y, s);
arb_set(y, s);
fmprb_clear(s);
fmprb_clear(t);
arb_clear(s);
arb_clear(t);
}
}

37
arb/fmprb_wrappers.c
View file

@ -1,37 +0,0 @@
/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2014 Fredrik Johansson
******************************************************************************/
#include "arb.h"
void arb_div_2expm1_ui(arb_t z, const arb_t x, ulong n, long prec)
{
fmprb_t t;
fmprb_init(t);
arb_get_fmprb(t, x);
fmprb_div_2expm1_ui(t, t, n, prec);
arb_set_fmprb(z, t);
fmprb_clear(t);
}

21
arb/test/t-div_2expm1_ui.c
View file

@ -49,12 +49,26 @@ int main()
prec = 2 + n_randint(state, 10000);
arb_randtest(a, state, 1 + n_randint(state, 10000), 10);
n = 1 + (n_randtest(state) % (10 * prec));
if (n_randint(state, 2))
n = 1 + (n_randtest(state) % (10 * prec));
else
n = n_randtest(state);
arb_div_2expm1_ui(b, a, n, prec);
arb_one(c);
arb_mul_2exp_si(c, c, n);
if (n >= (1UL << (FLINT_BITS-1)))
{
arb_mul_2exp_si(c, c, (1UL << (FLINT_BITS-2)));
arb_mul_2exp_si(c, c, (1UL << (FLINT_BITS-2)));
arb_mul_2exp_si(c, c, n - (1UL << (FLINT_BITS-1)));
}
else
{
arb_mul_2exp_si(c, c, n);
}
arb_sub_ui(c, c, 1, prec);
arb_div(c, a, c, prec);
@ -64,13 +78,14 @@ int main()
if (!arb_overlaps(b, c))
{
printf("FAIL: containment\n\n");
printf("n = %lu\n", n);
printf("a = "); arb_print(a); printf("\n\n");
printf("b = "); arb_print(b); printf("\n\n");
printf("c = "); arb_print(c); printf("\n\n");
abort();
}
if ((acc2 < FLINT_MIN(prec, acc1) - 10) &&
if (n > 0 && (acc2 < FLINT_MIN(prec, acc1) - 10) &&
!(acc1 == -ARF_PREC_EXACT && acc2 == -ARF_PREC_EXACT))
{
printf("FAIL: poor accuracy\n\n");

4
doc/source/fmprb.rst
View file

@ -437,10 +437,6 @@ Arithmetic
where the triangle inequality has been applied to the numerator and
the reverse triangle inequality has been applied to the denominator.
.. function:: void fmprb_div_2expm1_ui(fmprb_t y, const fmprb_t x, ulong n, long prec)
Sets `y = x / (2^n - 1)`, rounded to *prec* bits.
.. function:: void fmprb_addmul(fmprb_t z, const fmprb_t x, const fmprb_t y, long prec)
.. function:: void fmprb_addmul_ui(fmprb_t z, const fmprb_t x, ulong y, long prec)

3
fmprb.h
View file

@ -292,9 +292,6 @@ fmprb_inv(fmprb_t y, const fmprb_t x, long prec)
fmprb_ui_div(y, 1, x, prec);
}
void fmprb_div_2expm1_ui(fmprb_t y, const fmprb_t x, ulong n, long prec);
void fmprb_mul_fmpr_naive(fmprb_t z, const fmprb_t x, const fmpr_t y, long prec);
void fmprb_mul_main_naive(fmprb_t z, const fmprb_t x, const fmprb_t y, long prec);
void fmprb_mul_naive(fmprb_t z, const fmprb_t x, const fmprb_t y, long prec);

96
fmprb/test/t-div_2expm1_ui.c
View file

@ -1,96 +0,0 @@
/*=============================================================================
This file is part of ARB.
ARB is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
ARB is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with ARB; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
=============================================================================*/
/******************************************************************************
Copyright (C) 2013 Fredrik Johansson
******************************************************************************/
#include "fmprb.h"
int main()
{
long iter;
flint_rand_t state;
printf("div_2expm1_ui....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 100000; iter++)
{
fmprb_t a, b, c;
ulong n;
long prec, acc1, acc2;
fmpz_t t;
fmprb_init(a);
fmprb_init(b);
fmprb_init(c);
fmpz_init(t);
prec = 2 + n_randint(state, 10000);
fmprb_randtest(a, state, 1 + n_randint(state, 10000), 10);
n = 1 + (n_randtest(state) % (10 * prec));
fmprb_div_2expm1_ui(b, a, n, prec);
fmprb_one(c);
fmpz_set_ui(fmpr_expref(fmprb_midref(c)), n);
fmprb_sub_ui(c, c, 1, prec);
fmprb_div(c, a, c, prec);
acc1 = fmprb_rel_accuracy_bits(a);
acc2 = fmprb_rel_accuracy_bits(b);
if (!fmprb_overlaps(b, c))
{
printf("FAIL: containment\n\n");
printf("a = "); fmprb_print(a); printf("\n\n");
printf("b = "); fmprb_print(b); printf("\n\n");
printf("c = "); fmprb_print(c); printf("\n\n");
abort();
}
if ((acc2 < FLINT_MIN(prec, acc1) - 10) &&
!(acc1 == -FMPR_PREC_EXACT && acc2 == -FMPR_PREC_EXACT))
{
printf("FAIL: poor accuracy\n\n");
printf("prec=%ld, acc1=%ld, acc2=%ld\n\n", prec, acc1, acc2);
printf("n = %lu\n\n", n);
printf("a = "); fmprb_print(a); printf("\n\n");
printf("b = "); fmprb_print(b); printf("\n\n");
printf("c = "); fmprb_print(c); printf("\n\n");
abort();
}
fmprb_clear(a);
fmprb_clear(b);
fmprb_clear(c);
fmpz_clear(t);
}
flint_randclear(state);
flint_cleanup();
printf("PASS\n");
return EXIT_SUCCESS;
}