Wherever I have seen, PETSc tutorial/documents etc. say that it is useful for linear algebra and usually specifies that sparse systems will benefit. What about dense matrices? I am concerned about solving $Ax=b$ for dense $A$.
I have written my own code for CG and QMR in Fortran. The basic construct is to rip apart the pseudo code and add BLAS routines wherever possible (
dgemv) with a little self tuning. How will this compare to PETSc?
I know the best answer would be for me to try it myself but because of reasons of time and others, that is not possible.
Any help is much appreciated.