88 lines
2.1 KiB
C
Executable File
88 lines
2.1 KiB
C
Executable File
/* asincosf.c: Computes asin or acos of a 32-bit float as outlined in [1]
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Copyright (C) 2001, 2002 Jesus Calvino-Fraga, jesusc@ieee.org
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This library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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This library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with this library; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/* [1] William James Cody and W. M. Waite. _Software manual for the
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elementary functions_, Englewood Cliffs, N.J.:Prentice-Hall, 1980. */
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/* Version 1.0 - Initial release */
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#include "math.h"
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#include <errno.h>
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#define P1 0.933935835E+0
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#define P2 -0.504400557E+0
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#define Q0 0.560363004E+1
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#define Q1 -0.554846723E+1
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#define Q2 0.100000000E+1
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#define P(g) (P2*g+P1)
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#define Q(g) ((Q2*g+Q1)*g+Q0)
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#ifdef SDCC_mcs51
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#define myconst code
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#else
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#define myconst const
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#endif
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float asincosf(const float x, const int isacos)
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{
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float y, g, r;
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int i;
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static myconst float a[2]={ 0.0, QUART_PI };
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static myconst float b[2]={ HALF_PI, QUART_PI };
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y=fabsf(x);
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i=isacos;
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if (y < EPS) r=y;
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else
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{
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if (y > 0.5)
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{
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i=1-i;
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if (y > 1.0)
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{
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errno=EDOM;
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return 0.0;
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}
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g=(0.5-y)+0.5;
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g=ldexpf(g,-1);
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y=sqrtf(g);
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y=-(y+y);
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}
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else
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{
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g=y*y;
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}
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r=y+y*((P(g)*g)/Q(g));
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}
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if (isacos)
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{
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if (x < 0.0)
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r=(b[i]+r)+b[i];
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else
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r=(a[i]-r)+a[i];
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}
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else
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{
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r=(a[i]+r)+a[i];
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if (x<0.0) r=-r;
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}
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return r;
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}
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