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add arb_sgn (sign function)

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This commit is contained in:
Fredrik Johansson 2016-02-17 21:32:39 +01:00
parent 02cfaa369c
commit 28d78c7c43
4 changed files with 126 additions and 0 deletions
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2
arb.h
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@ -206,6 +206,8 @@ void arb_neg_round(arb_t x, const arb_t y, slong prec);
void arb_abs(arb_t y, const arb_t x);
void arb_sgn(arb_t res, const arb_t x);
void _arb_digits_round_inplace(char * s, mp_bitcnt_t * shift, fmpz_t error, slong n, arf_rnd_t rnd);
int arb_set_str(arb_t res, const char * inp, slong prec);

45
arb/sgn.c Normal file
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@ -0,0 +1,45 @@
/*=============================================================================
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) 2016 Fredrik Johansson
******************************************************************************/
#include "arb.h"
void
arb_sgn(arb_t res, const arb_t x)
{
if (arb_is_zero(x))
{
arb_zero(res);
}
else if (arb_contains_zero(x))
{
arf_zero(arb_midref(res));
mag_one(arb_radref(res));
}
else
{
arb_set_si(res, arf_sgn(arb_midref(x)));
}
}

74
arb/test/t-sgn.c Normal file
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@ -0,0 +1,74 @@
/*=============================================================================
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) 2016 Fredrik Johansson
******************************************************************************/
#include "arb.h"
int main()
{
slong iter;
flint_rand_t state;
flint_printf("sgn....");
fflush(stdout);
flint_randinit(state);
for (iter = 0; iter < 1000; iter++)
{
arb_t a, b;
int result;
arb_init(a);
arb_init(b);
arb_randtest_special(a, state, 1 + n_randint(state, 200), 10);
arb_randtest_special(b, state, 1 + n_randint(state, 200), 10);
arb_sgn(b, a);
result = 1;
if (arb_contains_zero(a))
result = result & arb_contains_si(b, 0);
if (arb_contains_positive(a))
result = result & arb_contains_si(b, 1);
if (arb_contains_negative(a))
result = result & arb_contains_si(b, -1);
if (!result)
{
flint_printf("FAIL\n\n");
flint_printf("a = "); arb_print(a); flint_printf("\n\n");
flint_printf("b = "); arb_print(b); flint_printf("\n\n");
abort();
}
arb_clear(a);
arb_clear(b);
}
flint_randclear(state);
flint_cleanup();
flint_printf("PASS\n");
return EXIT_SUCCESS;
}

5
doc/source/arb.rst
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@ -602,6 +602,11 @@ Arithmetic
Sets *y* to the absolute value of *x*. No attempt is made to improve the
interval represented by *x* if it contains zero.
.. function:: void arb_sgn(arb_t y, const arb_t x)
Sets *y* to the sign function of *x*. The result is `[0 \pm 1]` if
*x* contains both zero and nonzero numbers.
.. function:: void arb_add(arb_t z, const arb_t x, const arb_t y, slong prec)
.. function:: void arb_add_arf(arb_t z, const arb_t x, const arf_t y, slong prec)