Thanks for looking through the patch Brian. > One question: it looks like this > extrapolates a vector quantity. For simplicity, would it make sense > to work with scalars as in the gsl_sum routines -- since presumably > that is the common case -- or is there some application where vector > extrapolation is unavoidable? (could each component can be > extrapolated independently?)
You're right that each component could be extrapolated independently. I wrote it using vectors because doing so allows using BLAS calls for the linear algebra and speeds up many component use cases. I'd prefer to keep the code vector-capable under the covers under the theory that people extrapolating only a scalar at a time aren't all that worried about speed. My vector use case arose from testing convergence orders for timesteppers (non-GSL, but similar in interface) that manipulate vectors of state variables. If you'd like, I can submit an additional patch that 1) Renames gsl_extrap_richardson to something like gsl_extrap_richardson_vector, 2) Provides a scalar-only gsl_extrap_richardson that wraps up scalars and calls the gsl_extrap_richardson_vector routines under the covers, and 3) Exercises the scalar-only wrappers fully in the test suite. That way if someone later does need a faster scalar-only version, he or she can change over the underlying implementation without fear of regression. - Rhys
