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Length: 913 (0x391)
Types: TextFile
Notes: UNIX file
Names: »atan.c«
└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
└─⟦f4b8d8c84⟧ UNIX Filesystem
└─⟦this⟧ »libm/atan.c«
/*
* Compute the inverse tangent function.
* (Hart 5100, 17.24)
*/
#include <math.h>
static double tanntab[] ={
0.12097470017580907217240715e+04,
0.30310745956115083044212807e+04,
0.27617198246138834959053784e+04,
0.11141290728455183546172942e+04,
0.19257920144815596134742860e+03,
0.11322159411676465523624500e+02,
0.97627215917176330369830000e-01
};
static double tanmtab[] ={
0.12097470017580907287514197e+04,
0.34343235961975351716547069e+04,
0.36645449563283749893504796e+04,
0.18216003392918464941509225e+04,
0.42307164648090478045242060e+03,
0.39917884248653798150199900e+02,
0.10000000000000000000000000e+01
};
double
atan(x)
double x;
{
double r;
register int i, s;
s = 0;
i = 0;
if (x < 0.0) {
s = 1;
x = -x;
}
if (x > 1.0) {
i = 1;
x = 1/x;
}
r = x * x;
r = x * (_pol(r, tanntab, 7)/_pol(r, tanmtab, 7));
if (i)
r = PI/2.0 - r;
if (s)
r = -r;
return (r);
}