[Help-gsl] About create_givens and precision

[Miguel García Torres]

Hi all,

I am porting some GSL C functions to Java. In function
gsl_linalg_hesstri_decomp, there are several calls to
the create_givens one to calculate the cosine and sin. However  when I have
very small values (~10^-15),
there are some differences and this usually causes big differences that are
propagated through the iterations.

I tried setting the key strictfp to the Java class to restrict the
floating-point <http://en.wikipedia.org/wiki/Floating-point> calculations;
however I get the
same problem.
Should I consider that values under 1e-12 should be set to 0? Did anybody
experience something similar?
If so what did you do? How can I know the precision of GSL (I am using Linux
Ubuntu)?

Thanks in advance,

PS. I didn't find this question on previus emails.