Actual source code: richscale.c
petsc-3.10.5 2019-03-28
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      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: .keywords: KSP, Richardson, set, scale
     20: @*/
     21: PetscErrorCode  KSPRichardsonSetScale(KSP ksp,PetscReal scale)
     22: {

     28:   PetscTryMethod(ksp,"KSPRichardsonSetScale_C",(KSP,PetscReal),(ksp,scale));
     29:   return(0);
     30: }

     32: /*@
     33:     KSPRichardsonSetSelfScale - Sets Richardson to automatically determine optimal scaling at each iteration to minimize the 2-norm of the
     34:        preconditioned residual

     36:     Logically Collective on KSP

     38:     Input Parameters:
     39: +   ksp - the iterative context
     40: -   scale - PETSC_TRUE or the default of PETSC_FALSE

     42:     Options Database Keys:
     43: . -ksp_richardson_self_scale - Use self-scaling

     45:     Level: intermediate

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

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

     54: .keywords: KSP, Richardson, set, scale
     55: @*/
     56: PetscErrorCode  KSPRichardsonSetSelfScale(KSP ksp,PetscBool scale)
     57: {

     63:   PetscTryMethod(ksp,"KSPRichardsonSetSelfScale_C",(KSP,PetscBool),(ksp,scale));
     64:   return(0);
     65: }