cast PetscScalar to double

[Fredrik Bengzon]

Hi
I'm using a Petsc 3 installation compiled with support for complex 
numbers. However, in the code I have made frequent use of the stl 
library and the standard type double. This now gives a compilation error 
since PetscScalar can not be casted into double. Do you know of a quick 
workaround or do I have to replace every instance of double with 
PetscScalar?
Regards,
Fredrik Bengzon