progress on powl.

Steve Kargl sgk at
Sat Dec 16 01:33:31 UTC 2017


As expect no one elase is working on powl, I have
dusted off my work-in-progress that is now some
1+ year in the works. I've now got a sort of 
working version in very limited testing.

% ./testl -a 1.2345 3.124
libmu = LD80C(0xf7303d48d62e9df4, 0,  1.93115964943387024991e+00L),
mpfru = LD80C(0xf7303d48d62e9df5, 0,  1.93115964943387025002e+00L),
 ulp = 0.73609
I'm still slowing working out some thresholds and
few other kinks.  The biggest problem is that 
src/e_pow.c may be the worse commented code that 
I've had the pleasure to read.  There are 3 polynomial
approximations.  One is easy to work.  The other two
are gaint mysteries at moment.

I'll note that src/e_powf.c uses the same polynomials
and it appears that these use naively rounded coefficients.
I suspect that these polynomials can be reduced to
lower order, but have pursued that yet.



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