MatStructure#

Indicates if two matrices have the same nonzero structure

Synopsis#

typedef enum {
  DIFFERENT_NONZERO_PATTERN,
  SUBSET_NONZERO_PATTERN,
  SAME_NONZERO_PATTERN,
  UNKNOWN_NONZERO_PATTERN
} MatStructure;

Values#

SAME_NONZERO_PATTERN - the two matrices have identical nonzero patterns
DIFFERENT_NONZERO_PATTERN - the two matrices may have different nonzero patterns
SUBSET_NONZERO_PATTERN - the nonzero pattern of the second matrix is a subset of the nonzero pattern of the first matrix
UNKNOWN_NONZERO_PATTERN - there is no known relationship between the nonzero patterns. In this case the implementations may try to detect a relationship to optimize the operation

Note#

Certain matrix operations (such as MatAXPY()) can run much faster if the sparsity pattern of the matrices are the same. But actually determining if the patterns are the same may be costly. This provides a way for users who know something about the sparsity patterns to provide this information to certain PETSc routines.