PETSc version 3.16.6

MatMFFDSetHHistory

Sets an array to collect a history of the differencing values (h) computed for the matrix-free product.

#include "petscmat.h"   
PetscErrorCode  MatMFFDSetHHistory(Mat J,PetscScalar history[],PetscInt nhistory)

Logically Collective on Mat

	J	- the matrix-free matrix context
	history	- space to hold the history
	nhistory	- number of entries in history, if more entries are generated than nhistory, then the later ones are discarded

Use MatMFFDResetHHistory() to reset the history counter and collect a new batch of differencing parameters, h.

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