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libsrc.lzh
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LibSrc
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Math
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exp.c
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C/C++ Source or Header
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1990-04-07
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1KB
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52 lines
#include <stdio.h>
#include <math.h>
#include "pml.h"
#include "cordic.h"
static char funcname[] = "exp";
extern CORDIC_Table CORDIC_Table0[];
extern CORDIC_Table CORDIC_Table1[];
double
exp(x)
double x;
{
double t, y, z;
double x0, y0, z0;
double D, temp;
int Q;
struct exception xcpt;
if (x > LOGE_MAXDOUBLE) {
xcpt.type = OVERFLOW;
xcpt.name = funcname;
xcpt.arg1 = x;
if (!matherr(&xcpt)) {
fprintf(stderr, "%s: OVERFLOW error\n", funcname);
errno = ERANGE;
xcpt.retval = MAXDOUBLE;
}
}
else if (x <= LOGE_MINDOUBLE) {
xcpt.type = UNDERFLOW;
xcpt.name = funcname;
xcpt.arg1 = x;
if (!matherr(&xcpt)) {
fprintf(stderr, "%s: OVERFLOW error\n", funcname);
errno = ERANGE;
xcpt.retval = 0.0;
}
}
else {
t = x / LN2;
D = modf(t, &temp);
Q = temp;
x0 = y0 = 1.0;
z0 = D * LN2;
CORDIC_rotate1(1, CORDIC_Table1, &x0, &y0, &z0);
xcpt.retval = ldexp(x0 / CORDIC_Table1->kval, Q);
}
return (xcpt.retval);
}