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/* atan2.c -- Arc tangent of two intervals.
Copyright 2009, 2010,
Spaces project, Inria Lorraine
and Salsa project, INRIA Rocquencourt,
and Arenaire project, Inria Rhone-Alpes, France
and Lab. ANO, USTL (Univ. of Lille), France
This file is part of the MPFI Library.
The MPFI Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version.
The MPFI Library 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 Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the MPFI Library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
MA 02110-1301, USA. */
#include "mpfi-impl.h"
int
mpfi_atan2 (mpfi_ptr a, mpfi_srcptr b, mpfi_srcptr c)
{
int inexact_left, inexact_right, inexact=0;
mpfi_t tmp;
if ( MPFI_NAN_P (b) || MPFI_NAN_P (c) ) {
mpfr_set_nan (&(a->left));
mpfr_set_nan (&(a->right));
MPFR_RET_NAN;
}
mpfi_init2 (tmp, mpfi_get_prec (a));
if (MPFI_IS_POS (b)) {
if (MPFI_IS_POS (c)) {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->left), &(c->right), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->right), &(c->left), MPFI_RNDU);
}
else if (MPFI_IS_NEG (c)) {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->right), &(c->right), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->left), &(c->left), MPFI_RNDU);
}
else {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->left), &(c->right), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->left), &(c->left), MPFI_RNDU);
}
}
else if (MPFI_IS_NEG (b)) {
if (MPFI_IS_POS (c)) {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->left), &(c->left), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->right), &(c->right), MPFI_RNDU);
}
else if (MPFI_IS_NEG (c)) {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->right), &(c->left), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->left), &(c->right), MPFI_RNDU);
}
else {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->right), &(c->left), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->right), &(c->right), MPFI_RNDU);
}
}
else {
if (MPFI_IS_POS (c)) {
inexact_left = mpfr_atan2 (&(tmp->left), &(b->left), &(c->left), MPFI_RNDD);
inexact_right = mpfr_atan2 (&(tmp->right), &(b->right), &(c->left), MPFI_RNDU);
}
else {
inexact_left = -mpfr_const_pi (&(tmp->left), MPFI_RNDU);
mpfr_neg (&(tmp->left), &(tmp->left), MPFI_RNDD);
inexact_right = mpfr_const_pi (&(tmp->right), MPFI_RNDU);
}
}
if (mpfr_sgn (&(tmp->left)) == 0) {
/* +0 as left endpoint */
mpfr_setsign (&(tmp->left), &(tmp->left), 0, MPFI_RNDU);
}
if (mpfr_sgn (&(tmp->right)) == 0) {
/* -0 as right endpoint */
mpfr_setsign (&(tmp->right), &(tmp->right), 1, MPFI_RNDD);
}
mpfi_set (a, tmp);
mpfi_clear (tmp);
if (inexact_left)
inexact += 1;
if (inexact_right)
inexact += 2;
return inexact;
}
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