Dear Brian, 2010/2/10 Brian Gough <[email protected]>: > At Tue, 2 Feb 2010 08:12:53 +0300, > Alexey Balakin wrote: >> I think a formula for discrete Hankel transform (DHT) contain a bug. >> The following code should give the same arrays b[i]=a[i] (at least >> with accuracy of numeric error). But it is possible only if one >> introduce additional multiplier f=j_{\nu, M} (in notation of GSL >> documentation). Note, here I use f*f because I do 2 transforms (like >> forward and backward). >> >> So, I suggest to note this in documentation (as GSL "feature"), or >> change the formula and the code of gsl_dht_apply() function to >> additional multiplication by j_{\nu, M}. > > Thanks for the email. I agree this is a bit confusing, I've added an > extra note to the documentation about the overall scaling factor. The > choice of factors in the transform is intentional because the test > code mentions it explicitly. I think the convention may come from one > of the original papers.
Good. >> One more comment. I think that it will be nice if gsl_dht_apply() >> can handle the same arrays for input and output :) . > > Unfortunately I don't think it's possible to do the transform > in-place. It's a pity but I can write my own wrapper function (what I really do now). -- All the best, Alexey Balakin _______________________________________________ Bug-gsl mailing list [email protected] http://lists.gnu.org/mailman/listinfo/bug-gsl
