GCC Code Coverage Report
Directory: ./ Exec Total Coverage
File: lib/libm/src/s_ctanf.c Lines: 0 41 0.0 %
Date: 2017-11-13 Branches: 0 8 0.0 %

Line Branch Exec Source
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/*	$OpenBSD: s_ctanf.c,v 1.2 2011/07/20 19:28:33 martynas Exp $	*/
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/*
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 * Copyright (c) 2008 Stephen L. Moshier <steve@moshier.net>
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 *
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 * Permission to use, copy, modify, and distribute this software for any
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 * purpose with or without fee is hereby granted, provided that the above
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 * copyright notice and this permission notice appear in all copies.
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 *
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 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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 */
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/*							ctanf()
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 *
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 *	Complex circular tangent
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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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 * void ctanf();
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 * cmplxf z, w;
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 *
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 * ctanf( &z, &w );
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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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 * If
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 *     z = x + iy,
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 *
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 * then
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 *
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 *           sin 2x  +  i sinh 2y
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 *     w  =  --------------------.
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 *            cos 2x  +  cosh 2y
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 *
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 * On the real axis the denominator is zero at odd multiples
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 * of PI/2.  The denominator is evaluated by its Taylor
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 * series near these points.
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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      -10,+10     30000       3.3e-7       5.1e-8
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 */
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#include <complex.h>
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#include <math.h>
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#define MACHEPF 3.0e-8
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#define MAXNUMF 1.0e38f
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static const double DP1 = 3.140625;
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static const double DP2 = 9.67502593994140625E-4;
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static const double DP3 = 1.509957990978376432E-7;
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static float
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_redupif(float xx)
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{
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	float x, t;
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	long i;
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	x = xx;
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	t = x/(float)M_PI;
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	if(t >= 0.0)
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		t += 0.5;
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	else
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		t -= 0.5;
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	i = t;	/* the multiple */
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	t = i;
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	t = ((x - t * DP1) - t * DP2) - t * DP3;
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	return(t);
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}
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/*  Taylor series expansion for cosh(2y) - cos(2x)	*/
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static float
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_ctansf(float complex z)
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{
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	float f, x, x2, y, y2, rn, t, d;
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	x = fabsf(2.0f * crealf(z));
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	y = fabsf(2.0f * cimagf(z));
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	x = _redupif(x);
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	x = x * x;
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	y = y * y;
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	x2 = 1.0f;
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	y2 = 1.0f;
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	f = 1.0f;
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	rn = 0.0f;
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	d = 0.0f;
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	do {
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		rn += 1.0f;
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		f *= rn;
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		rn += 1.0f;
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		f *= rn;
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		x2 *= x;
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		y2 *= y;
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		t = y2 + x2;
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		t /= f;
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		d += t;
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		rn += 1.0f;
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		f *= rn;
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		rn += 1.0f;
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		f *= rn;
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		x2 *= x;
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		y2 *= y;
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		t = y2 - x2;
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		t /= f;
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		d += t;
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	}
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	while (fabsf(t/d) > MACHEPF)
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		;
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	return(d);
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}
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float complex
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ctanf(float complex z)
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{
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	float complex w;
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	float d;
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	d = cosf( 2.0f * crealf(z) ) + coshf( 2.0f * cimagf(z) );
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	if(fabsf(d) < 0.25f)
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		d = _ctansf(z);
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	if (d == 0.0f) {
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		/*mtherr( "ctanf", OVERFLOW );*/
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		w = MAXNUMF + MAXNUMF * I;
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		return (w);
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	}
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	w = sinf (2.0f * crealf(z)) / d + (sinhf (2.0f * cimagf(z)) / d) * I;
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	return (w);
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}