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Length: 835 (0x343)
Types: TextFile
Notes: UNIX file
Names: »tan.c«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦f4b8d8c84⟧ UNIX V7 Filesystem
└─ ⟦this⟧ »libm/tan.c«
/*
* Evaluate the tangent function.
* (Hart 4245, 17.08)
*/
#include <math.h>
static double tanntab[] ={
-0.16045331195592187943926861e+05,
0.12697548376580828837860720e+04,
-0.17135185514886110932101000e+02,
0.28208772971655103151400000e-01
};
static double tanmtab[] ={
-0.20429550186600697853114142e+05,
0.58173599554655686739034190e+04,
-0.18149310354089045993457500e+03,
0.10000000000000000000000000e+01
};
double
tan(x)
double x;
{
double r;
register int i, s;
x = modf(x/(2.0*PI), &r);
i = 0;
s = 0;
if (x > 0.5)
x -= 0.5;
if (x > 0.25) {
s = 1;
x = 0.5 - x;
}
if (x > 0.125) {
i = 1;
x = 0.25 - x;
}
x *= 8.0;
r = x * x;
r = x * (_pol(r, tanntab, 4)/_pol(r, tanmtab, 4));
if (i) {
if (r < 1.0/I) {
errno = ERANGE;
return (I);
}
r = 1/r;
}
if (s)
r = -r;
return (r);
}