Re: Double-precision floating point arithmetics behaves differently in Guile and in C

[Panicz Maciej Godek]

niedz., 26 wrz 2021 o 21:11 Matt Wette <matt.wette@gmail.com> napisał(a):

> Your post is a little vague.  Are you comparing singular values vectors
> of A vs
> eigenvalues, eigenvectors of A'*A ?  Also, SVD is iterative and
> different algorithms may yield
> different results (and some of the SVD algorithms out there are not great).
>   Are you using the exact same algorithm but noticing that (op x y) in
> Guile
> behaves differently than (x op y) in C?
>
>
Yes.
I mean, I have used exactly the same algorithm (obtained by mechanically
transforming the scmutils code into C), and I've been looking at its
operation, and noticed that the results of floating point operations
differed between Guile and C for the same input data.

However, it turned out that it wasn't those differences that caused the
trouble, and I currently believe that the numerical differences can be
tolerable for my application.


>