float of struve_h functions?



Maxima won't win a speed contest for numerical evaluation of struve_h, but at least the 
value of struve_h(0, 1000.0b0) agrees with Wolfram alpha:

(%i11) fpprec : 56$

Takes about 2 seconds on my i3:

 (%i12) struve_h(0, 1000.0b0), max_fpprec : 10000;
 (%o12) 5.3525371133763518099863310575438959362152058389955848882b-3

Wolfram alpha (input StruveH[0,1000])

 (%i13) 0.0053525371133763518099863310575438959362152058389955848882b0$

 (%i14) (%-%o12)/%;
 (%o14) -5.580619564334294774727172516159399253437892869615357299b-57 

For numerical evaluation, the hypergeometric code only uses convergent power series--it 
uses no divergent asymptotic expansions. I think there is a useful divergent expansion
for struve_h(0,x) for x --> infinity.

I suppose the message "fpprec.Exceeded maximum allowed" could be changed to a suggestion
to increase max_fpprec. It's sad that the message is printed multiple times, but avoiding
that is hard, I think.

--Barton