Actual source code: richscale.c


  2: #include <../src/ksp/ksp/impls/rich/richardsonimpl.h>

  4: /*@
  5:     KSPRichardsonSetScale - Set the damping factor; if this routine is not called, the factor
  6:     defaults to 1.0.

  8:     Logically Collective on ksp

 10:     Input Parameters:
 11: +   ksp - the iterative context
 12: -   scale - the relaxation factor

 14:     Options Database Keys:
 15: . -ksp_richardson_self <scale> - Set the scale factor

 17:     Level: intermediate

 19:     .seealso: KSPRICHARDSON, KSPRichardsonSetSelfScale()
 20: @*/
 21: PetscErrorCode  KSPRichardsonSetScale(KSP ksp,PetscReal scale)
 22: {
 25:   PetscTryMethod(ksp,"KSPRichardsonSetScale_C",(KSP,PetscReal),(ksp,scale));
 26:   return 0;
 27: }

 29: /*@
 30:     KSPRichardsonSetSelfScale - Sets Richardson to automatically determine optimal scaling at each iteration to minimize the 2-norm of the
 31:        preconditioned residual

 33:     Logically Collective on ksp

 35:     Input Parameters:
 36: +   ksp - the iterative context
 37: -   scale - PETSC_TRUE or the default of PETSC_FALSE

 39:     Options Database Keys:
 40: . -ksp_richardson_self_scale - Use self-scaling

 42:     Level: intermediate

 44:     Notes:
 45:     Requires two extra work vectors. Uses an extra VecAXPY() and VecDotNorm2() per iteration.

 47:     Developer Notes:
 48:     Could also minimize the 2-norm of the true residual with one less work vector

 50:     .seealso: KSPRICHARDSON, KSPRichardsonSetScale()
 51: @*/
 52: PetscErrorCode  KSPRichardsonSetSelfScale(KSP ksp,PetscBool scale)
 53: {
 56:   PetscTryMethod(ksp,"KSPRichardsonSetSelfScale_C",(KSP,PetscBool),(ksp,scale));
 57:   return 0;
 58: }