petsc-3.9.4 2018-09-11

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

Notes: 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

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