OPERATORS

There were several directions that we felt we could follow with the design of operators. The first approach is what SEP traditionally did within Fortran77. Specifically to define all of operators through subroutine calls. This approach is advantageous because specifying whether to run the adjoint or the forward operator would involve changing one parameter in the subroutine call:

operator(input,output,adjoint)

On the other hand addition

is another valid operator and it not expressed through subroutines. We decided that it was more important to keep the operator concept consistent with its mathematical counterpart as much as possible.

This approach allows compound statements like:

D = A.conv.B - C

where A, B, C, and D are all sep_type's.