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Optimize the case of pure imaginary arguments. Calls like this are

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common, e.g., in DFT implementations.

Discussed with:	bde, kargl
This commit is contained in:
David Schultz 2011-10-16 05:37:01 +00:00
parent e62394861d
commit 4ce31585dc
2 changed files with 9 additions and 2 deletions
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7
lib/msun/src/s_cexp.c
View File

@ -56,8 +56,12 @@ cexp(double complex z)
/* cexp(x + I 0) = exp(x) + I 0 */
if ((hy | ly) == 0)
return (cpack(exp(x), y));
EXTRACT_WORDS(hx, lx, x);
/* cexp(0 + I y) = cos(y) + I sin(y) */
if (((hx & 0x7fffffff) | lx) == 0)
return (cpack(cos(y), sin(y)));
if (hy >= 0x7ff00000) {
EXTRACT_WORDS(hx, lx, x);
if (lx != 0 || (hx & 0x7fffffff) != 0x7ff00000) {
/* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
return (cpack(y - y, y - y));
@ -70,7 +74,6 @@ cexp(double complex z)
}
}
GET_HIGH_WORD(hx, x);
if (hx >= exp_ovfl && hx <= cexp_ovfl) {
/*
* x is between 709.7 and 1454.3, so we must scale to avoid

4
lib/msun/src/s_cexpf.c
View File

@ -57,6 +57,10 @@ cexpf(float complex z)
if (hy == 0)
return (cpackf(expf(x), y));
GET_FLOAT_WORD(hx, x);
/* cexp(0 + I y) = cos(y) + I sin(y) */
if ((hx & 0x7fffffff) == 0)
return (cpackf(cosf(y), sinf(y)));
if (hy >= 0x7f800000) {
if ((hx & 0x7fffffff) != 0x7f800000) {
/* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */