48 lines
647 B
C
48 lines
647 B
C
/*
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asin(arg) and acos(arg) return the arcsin, arccos,
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respectively of their arguments.
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Arctan is called after appropriate range reduction.
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*/
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#include <math.h>
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#include <errno.h>
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static double pio2 = 1.570796326794896619231e0;
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double
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asin(double arg)
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{
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double temp;
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int sign;
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sign = 0;
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if(arg < 0) {
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arg = -arg;
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sign++;
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}
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if(arg > 1) {
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errno = EDOM;
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return 0;
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}
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temp = sqrt(1 - arg*arg);
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if(arg > 0.7)
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temp = pio2 - atan(temp/arg);
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else
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temp = atan(arg/temp);
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if(sign)
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temp = -temp;
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return temp;
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}
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double
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acos(double arg)
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{
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if(arg > 1 || arg < -1) {
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errno = EDOM;
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return 0;
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}
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return pio2 - asin(arg);
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}
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