PETSc version 3.17.4
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# MatMFFDCheckPositivity

Checks that all entries in U + h*a are positive or zero, decreases h until this is satisfied.

### Synopsis

    #include "petscmat.h"
    PetscErrorCode  MatMFFDCheckPositivity(void *dummy,Vec U,Vec a,PetscScalar *h)

Logically Collective on Vec

### Input Parameters

| U | - base vector that is added to
| a | - vector that is added
| h | - scaling factor on a
| dummy | - context variable (unused)

### Options Database Keys

| -mat_mffd_check_positivity <bool> | - Insure that U + h*a is nonnegative

### Notes

This is rarely used directly, rather it is passed as an argument to MatMFFDSetCheckh()

### See Also

MatMFFDSetCheckh()

### Level

advanced

### Location

src/mat/impls/mffd/mffd.c
Index of all Mat routines
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