* Update the comments to agree with commit r226595.

* While here, fix a nearby typo in a comment.
This commit is contained in:
Steve Kargl 2014-07-13 23:10:39 +00:00
parent f26bcf99e0
commit d781108453
Notes: svn2git 2020-12-20 02:59:44 +00:00
svn path=/head/; revision=268597

View File

@ -19,20 +19,20 @@ __FBSDID("$FreeBSD$");
* 1. Compute and return log2(x) in two pieces:
* log2(x) = w1 + w2,
* where w1 has 53-24 = 29 bit trailing zeros.
* 2. Perform y*log2(x) = n+y' by simulating muti-precision
* 2. Perform y*log2(x) = n+y' by simulating multi-precision
* arithmetic, where |y'|<=0.5.
* 3. Return x**y = 2**n*exp(y'*log2)
*
* Special cases:
* 1. (anything) ** 0 is 1
* 2. (anything) ** 1 is itself
* 3. (anything) ** NAN is NAN
* 3. (anything) ** NAN is NAN except 1 ** NAN = 1
* 4. NAN ** (anything except 0) is NAN
* 5. +-(|x| > 1) ** +INF is +INF
* 6. +-(|x| > 1) ** -INF is +0
* 7. +-(|x| < 1) ** +INF is +0
* 8. +-(|x| < 1) ** -INF is +INF
* 9. +-1 ** +-INF is NAN
* 9. +-1 ** +-INF is 1
* 10. +0 ** (+anything except 0, NAN) is +0
* 11. -0 ** (+anything except 0, NAN, odd integer) is +0
* 12. +0 ** (-anything except 0, NAN) is +INF
@ -141,7 +141,7 @@ __ieee754_pow(double x, double y)
if(ly==0) {
if (iy==0x7ff00000) { /* y is +-inf */
if(((ix-0x3ff00000)|lx)==0)
return one; /* (-1)**+-inf is NaN */
return one; /* (-1)**+-inf is 1 */
else if (ix >= 0x3ff00000)/* (|x|>1)**+-inf = inf,0 */
return (hy>=0)? y: zero;
else /* (|x|<1)**-,+inf = inf,0 */