140 lines
3.3 KiB
C++
140 lines
3.3 KiB
C++
/* Translated into C++ by SciPy developers in 2024.
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* Original header with Copyright information appears below.
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*/
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/* tandg.c
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*
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* Circular tangent of argument in degrees
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*
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*
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*
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* SYNOPSIS:
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*
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* double x, y, tandg();
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*
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* y = tandg( x );
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*
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*
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*
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* DESCRIPTION:
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*
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* Returns the circular tangent of the argument x in degrees.
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*
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* Range reduction is modulo pi/4. A rational function
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* x + x**3 P(x**2)/Q(x**2)
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* is employed in the basic interval [0, pi/4].
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*
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*
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*
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* ACCURACY:
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*
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* Relative error:
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* arithmetic domain # trials peak rms
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* IEEE 0,10 30000 3.2e-16 8.4e-17
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*
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* ERROR MESSAGES:
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*
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* message condition value returned
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* tandg total loss x > 1.0e14 (IEEE) 0.0
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* tandg singularity x = 180 k + 90 INFINITY
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*/
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/* cotdg.c
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*
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* Circular cotangent of argument in degrees
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*
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*
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*
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* SYNOPSIS:
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*
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* double x, y, cotdg();
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*
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* y = cotdg( x );
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*
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*
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*
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* DESCRIPTION:
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*
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* Returns the circular cotangent of the argument x in degrees.
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*
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* Range reduction is modulo pi/4. A rational function
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* x + x**3 P(x**2)/Q(x**2)
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* is employed in the basic interval [0, pi/4].
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*
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*
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* ERROR MESSAGES:
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*
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* message condition value returned
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* cotdg total loss x > 1.0e14 (IEEE) 0.0
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* cotdg singularity x = 180 k INFINITY
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*/
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/*
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* Cephes Math Library Release 2.0: April, 1987
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* Copyright 1984, 1987 by Stephen L. Moshier
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* Direct inquiries to 30 Frost Street, Cambridge, MA 02140
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*/
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#pragma once
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#include "../config.h"
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#include "../error.h"
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namespace xsf {
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namespace cephes {
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namespace detail {
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constexpr double tandg_lossth = 1.0e14;
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XSF_HOST_DEVICE inline double tancot(double xx, int cotflg) {
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double x;
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int sign;
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/* make argument positive but save the sign */
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if (xx < 0) {
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x = -xx;
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sign = -1;
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} else {
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x = xx;
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sign = 1;
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}
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if (x > detail::tandg_lossth) {
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set_error("tandg", SF_ERROR_NO_RESULT, NULL);
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return 0.0;
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}
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/* modulo 180 */
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x = x - 180.0 * std::floor(x / 180.0);
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if (cotflg) {
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if (x <= 90.0) {
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x = 90.0 - x;
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} else {
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x = x - 90.0;
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sign *= -1;
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}
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} else {
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if (x > 90.0) {
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x = 180.0 - x;
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sign *= -1;
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}
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}
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if (x == 0.0) {
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return 0.0;
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} else if (x == 45.0) {
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return sign * 1.0;
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} else if (x == 90.0) {
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set_error((cotflg ? "cotdg" : "tandg"), SF_ERROR_SINGULAR, NULL);
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return std::numeric_limits<double>::infinity();
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}
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/* x is now transformed into [0, 90) */
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return sign * std::tan(x * detail::PI180);
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}
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} // namespace detail
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XSF_HOST_DEVICE inline double tandg(double x) { return (detail::tancot(x, 0)); }
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XSF_HOST_DEVICE inline double cotdg(double x) { return (detail::tancot(x, 1)); }
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} // namespace cephes
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} // namespace xsf
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