From: Denis Davydov <davydden@gmail.com>
Date: Fri, 1 Jan 2016 11:50:19 +0000 (+0100)
Subject: make sure that inside solve() PETSc preconditioner has a matrix set
X-Git-Tag: v8.4.0-rc2~114^2~1
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=babe68f61d1fb4bd4c279ae547576516fa165ddd;p=dealii.git

make sure that inside solve() PETSc preconditioner has a matrix set
---

diff --git a/source/lac/petsc_solver.cc b/source/lac/petsc_solver.cc
index bd8c986476..19372d48b3 100644
--- a/source/lac/petsc_solver.cc
+++ b/source/lac/petsc_solver.cc
@@ -95,6 +95,12 @@ namespace PETScWrappers
         ierr = KSPSetPC (solver_data->ksp, preconditioner.get_pc());
         AssertThrow (ierr == 0, ExcPETScError(ierr));
 
+        // make sure the preconditioner has an associated matrix set
+        const Mat B = preconditioner;
+        AssertThrow (B != NULL,
+                     ExcMessage("PETSc preconditioner should have an"
+                                "associated matrix set to be used in solver."));
+
         // setting the preconditioner overwrites the used matrices.
         // hence, we need to set the matrices after the preconditioner.
 #if DEAL_II_PETSC_VERSION_LT(3, 5, 0)