If I use MatISSetLocalMat with a preallocated MatCreateSeqAIJ local matrix, do I need to use MatISSetPreallocation for the global matrix ?

Here is the pseudo-code:

MatCreateIS(PETSC_COMM_WORLD, ..., &globalMat)

MatISSetPreallocation(globalMatrix, ...) // Is this necessary ?

MatCreateSeqAIJ(PETSC_COMM_SELF, ..., &localMatrix) // Prealloc done on the fly

MatSetValues(localMatrix, ...)

MatISSetLocalMat(globalMatrix, localMatrix)

Is it necessary to call MatISSetPreallocation for globalMatrix ? (prealloc should have been done locally for each local matrix, no ?)

Franck