OpenE2K
/
glibc
2
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Remove unnecessary factorial array 

kf is n! at the end of the loop, so storing the values is unnecessary.
This commit is contained in:
Siddhesh Poyarekar 2013-02-13 17:19:06 +05:30
parent 4e92d59e26
commit c2af38aa76
2 changed files with 5 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
ChangeLog
View File

@ -1,5 +1,7 @@
2013-02-13 Siddhesh Poyarekar <siddhesh@redhat.com>
* sysdeps/ieee754/dbl-64/mpexp.c (__mpexp): Remove NFA.
* sysdeps/ieee754/dbl-64/mpexp.c (__mpexp): Faster polynomial
evaluation.

13
sysdeps/ieee754/dbl-64/mpexp.c
View File

@ -50,14 +50,6 @@ __mpexp (mp_no *x, mp_no *y, int p)
6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 8
};
/* Factorials for the values of np above. */
static const double nfa[33] =
{
1.0, 1.0, 1.0, 1.0, 6.0, 6.0, 24.0, 24.0, 120.0, 24.0, 24.0,
120.0, 120.0, 120.0, 720.0, 720.0, 720.0, 720.0, 720.0, 720.0,
720.0, 720.0, 720.0, 720.0, 5040.0, 5040.0, 5040.0, 5040.0,
40320.0, 40320.0, 40320.0, 40320.0, 40320.0
};
static const int m1p[33] =
{
0, 0, 0, 0,
@ -130,7 +122,8 @@ __mpexp (mp_no *x, mp_no *y, int p)
e^x = 1 + (x * n!/1! + x^2 * n!/2! + x^3 * n!/3!) / n!
= 1 + (x * (n!/1! + x * (n!/2! + x * (n!/3! + x ...)))) / n!
n! is pre-computed and saved while k! is computed on the fly. */
k! is computed on the fly as KF and at the end of the polynomial loop, KF
is n!, which can be used directly. */
__cpy (&mps, &mpt2, p);
double kf = 1.0;
@ -145,7 +138,7 @@ __mpexp (mp_no *x, mp_no *y, int p)
__add (&mpt2, &mpk, &mpt1, p);
__mul (&mps, &mpt1, &mpt2, p);
}
__dbl_mp (nfa[p], &mpk, p);
__dbl_mp (kf, &mpk, p);
__dvd (&mpt2, &mpk, &mpt1, p);
__add (&mpone, &mpt1, &mpt2, p);