41 lines
567 B
C
41 lines
567 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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*
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* Arctan is called after appropriate range reduction.
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*/
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#include <u.h>
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#include <libc.h>
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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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return NaN();
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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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return NaN();
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return PIO2 - asin(arg);
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}
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