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/* $OpenBSD: s_catanf.c,v 1.3 2016/09/12 19:47:02 guenther 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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/* catanf() |
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* |
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* Complex circular arc 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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* float complex catanf(); |
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* float complex z, w; |
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* |
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* w = catanf( z ); |
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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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* 1 ( 2x ) |
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* Re w = - arctan(-----------) + k PI |
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* 2 ( 2 2) |
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* (1 - x - y ) |
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* |
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* ( 2 2) |
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* 1 (x + (y+1) ) |
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* Im w = - log(------------) |
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* 4 ( 2 2) |
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* (x + (y-1) ) |
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* |
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* Where k is an arbitrary integer. |
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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 -10,+10 30000 2.3e-6 5.2e-8 |
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* |
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*/ |
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#include <complex.h> |
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#include <math.h> |
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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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float complex |
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catanf(float complex z) |
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{ |
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float complex w; |
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float a, t, x, x2, y; |
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x = crealf(z); |
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y = cimagf(z); |
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if((x == 0.0f) && (y > 1.0f)) |
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goto ovrf; |
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x2 = x * x; |
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a = 1.0f - x2 - (y * y); |
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if (a == 0.0f) |
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goto ovrf; |
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t = 0.5f * atan2f(2.0f * x, a); |
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w = _redupif(t); |
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t = y - 1.0f; |
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a = x2 + (t * t); |
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if(a == 0.0f) |
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goto ovrf; |
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t = y + 1.0f; |
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a = (x2 + (t * t))/a; |
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w = w + (0.25f * logf (a)) * I; |
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return (w); |
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ovrf: |
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/*mtherr( "catanf", OVERFLOW );*/ |
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w = MAXNUMF + MAXNUMF * I; |
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return (w); |
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} |
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DEF_STD(catanf); |