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# define TGSOURCE "cos.c"
#include <errno.h>
#include <math.h>
#include "_tgmath.h"
/** cosine **/
TYPE TGFN(cos)(TYPE x)
{
int MAXLOOPS = 10;
int factorial = 1;
int i;
TYPE cosine = 1.0;
TYPE power = 1.0;
switch (fpclassify(x)) {
case FP_ZERO: return 1.0;
case FP_INFINITE: feraiseexcept(FE_INVALID); return NAN;
default: break;
}
if (0) {
errno = ERANGE; /* The result cannot be represented */
/* RETURN_FAILURE(CONSTANT(HUGE_VAL), A range error occurred); */
return TGHUGE;
}
/* TODO: make sure x is in the right domain */
/* TODO: tweak number of loops */
/* cos x = 1 - x^2/2! + x^4/4! -x^6/6! ... */
for (i = 1; i < MAXLOOPS; i++) {
power = power * x;
factorial = factorial * i;
if (i % 4 == 0) {
cosine += power / factorial;
} else if (i % 4 == 2) {
cosine -= power / factorial;
}
}
/* RETURN_SUCCESS(the cosine of ARGUMENT(x)); */
return cosine;
}
/***
compute cosine of ARGUMENT(x), in radians.
***/
/*
IMPLEMENTATION(The value returned on a domain error, CONSTANT(HUGE_VAL))
LINK(m)
STDC(1)
*/
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