53 lines
698 B
C
53 lines
698 B
C
/*
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* (c) copyright 1988 by the Vrije Universiteit, Amsterdam, The Netherlands.
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* See the copyright notice in the ACK home directory, in the file "Copyright".
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*
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* Author: Ceriel J.H. Jacobs
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*/
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/* $Header$ */
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#include <math.h>
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#include <errno.h>
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extern int errno;
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static double
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asin_acos(x, cosfl)
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double x;
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{
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int negative = x < 0;
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extern double sqrt(), atan();
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if (negative) {
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x = -x;
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}
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if (x > 1) {
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errno = EDOM;
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return 0;
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}
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if (x == 1) {
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x = M_PI_2;
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}
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else x = atan(x/sqrt(1-x*x));
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if (negative) x = -x;
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if (cosfl) {
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return M_PI_2 - x;
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}
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return x;
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}
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double
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asin(x)
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double x;
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{
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return asin_acos(x, 0);
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}
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double
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acos(x)
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double x;
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{
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return asin_acos(x, 1);
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}
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