petsc-3.13.6 2020-09-29

PCDiagonalScaleLeft

Scales a vector by the left scaling as needed by certain time-stepping codes.

#include "petscksp.h" 
PetscErrorCode  PCDiagonalScaleLeft(PC pc,Vec in,Vec out)

Logically Collective on PC

	pc	- the preconditioner context
	in	- input vector
	out	- scaled vector (maybe the same as in)

The system solved via the Krylov method is

          D M A D^{-1} y = D M b  for left preconditioning or

          D A M D^{-1} z = D b for right preconditioning

PCDiagonalScaleLeft() scales a vector by D. PCDiagonalScaleRight() scales a vector by D^{-1}.

If diagonal scaling is turned off and in is not out then in is copied to out

intermediate