# MATIS

MATIS = "is" - A matrix type to be used for using the Neumann-Neumann type preconditioners. This stores the matrices in globally unassembled form. Each processor assembles only its local Neumann problem and the parallel matrix vector product is handled "implicitly".

### Operations Provided

| MatMult() | - . MatZeroEntries()
| MatSetOption() | - . MatZeroRowsLocal()
| MatSetValuesLocal() | - - MatSetLocalToGlobalMapping()

### Options Database Keys

| -mat_type is | - sets the matrix type to "is" during a call to MatSetFromOptions()

Notes: Options prefix for the inner matrix are given by -is_mat_xxx

You must call MatSetLocalToGlobalMapping() before using this matrix type.

You can do matrix preallocation on the local matrix after you obtain it with MatISGetLocalMat()

### See Also

PC, MatISGetLocalMat(), MatSetLocalToGlobalMapping()

Level:advanced
Location:src/mat/impls/is/matis.c
Index of all Mat routines
Table of Contents for all manual pages
Index of all manual pages