Actual source code: lsqr_converged.c
petsc-3.7.1 2016-05-15
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      1: #include <petsc/private/kspimpl.h>
      2: #include <../src/ksp/ksp/impls/lsqr/lsqr.h>
      3: extern PetscErrorCode  KSPLSQRGetArnorm(KSP,PetscReal*,PetscReal*,PetscReal*);

      5: PetscErrorCode KSPConvergedLSQR(KSP solksp,PetscInt iter,PetscReal rnorm,KSPConvergedReason *reason,void *ctx)
      6: {
      7:   PetscReal atol;          /* Absolute convergence criterium */
      8:   PetscReal dtol;          /* Divergence criterium */
      9:   PetscReal rtol;          /* Relative convergence criterium */
     10:   PetscReal stop1;         /* Stop if: |r| < rtol*|b| + atol*|A|*|x| */
     11:   PetscReal stop2;         /* Stop if: |A^t.r|/(|A|*|r|) < atol */
     12:   Vec       x_sol;         /* Current solution vector */

     14:   PetscReal arnorm, anorm, bnorm, xnorm;        /* Norms of A*residual; matrix A; rhs; solution */

     16:   PetscInt       mxiter;   /* Maximum # of iterations */

     20:   *reason = KSP_CONVERGED_ITERATING;
     21:   if (iter == 0) return(0);

     23:   KSPCheckNorm(solksp,rnorm);

     25:   KSPGetTolerances(solksp, &rtol, &atol, &dtol, &mxiter);
     26:   if (iter > mxiter) {
     27:     *reason = KSP_DIVERGED_ITS;
     28:     return(0);
     29:   }

     31:   KSPGetSolution(solksp, &x_sol);
     32:   VecNorm(x_sol, NORM_2, &xnorm);

     34:   KSPLSQRGetArnorm(solksp, &arnorm, &bnorm, &anorm);
     35:   if (bnorm > 0.0) {
     36:     stop1 = rnorm / bnorm;
     37:     rtol  = rtol + atol * anorm*xnorm/bnorm;
     38:   } else {
     39:     stop1 = 0.0;
     40:     rtol  = 0.0;
     41:   }
     42:   stop2 = 0.0;
     43:   if (rnorm > 0.0) stop2 = arnorm / (anorm * rnorm);

     45:   /* Test for tolerances set by the user */
     46:   if (stop1 <= rtol) *reason = KSP_CONVERGED_RTOL;
     47:   if (stop2 <= atol) *reason = KSP_CONVERGED_ATOL;

     49:   /* Test for machine precision */
     50:   if (bnorm > 0) stop1 = stop1 / (1.0 + anorm*xnorm/bnorm);
     51:   else stop1 = 0.0;

     53:   stop1 = 1.0 + stop1;
     54:   stop2 = 1.0 + stop2;
     55:   if (stop1 <= 1.0) *reason = KSP_CONVERGED_RTOL;
     56:   if (stop2 <= 1.0) *reason = KSP_CONVERGED_ATOL;
     57:   return(0);
     58: }