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

pesser/dealii,pesser/dealii,kalj/dealii,angelrca/dealii,danshapero/dealii,maieneuro/dealii,sairajat/dealii,shakirbsm/dealii,EGP-CIG-REU/dealii,spco/dealii,gpitton/dealii,kalj/dealii,nicolacavallini/dealii,Arezou-gh/dealii,maieneuro/dealii,jperryhouts/dealii,JaeryunYim/dealii,Arezou-gh/dealii,Arezou-gh/dealii,kalj/dealii,kalj/dealii,jperryhouts/dealii,kalj/dealii,kalj/dealii,maieneuro/dealii,danshapero/dealii,pesser/dealii,shakirbsm/dealii,ESeNonFossiIo/dealii,Arezou-gh/dealii,EGP-CIG-REU/dealii,ESeNonFossiIo/dealii,gpitton/dealii,JaeryunYim/dealii,danshapero/dealii,angelrca/dealii,spco/dealii,jperryhouts/dealii,naliboff/dealii,ESeNonFossiIo/dealii,shakirbsm/dealii,sairajat/dealii,JaeryunYim/dealii,EGP-CIG-REU/dealii,nicolacavallini/dealii,maieneuro/dealii,angelrca/dealii,gpitton/dealii,nicolacavallini/dealii,shakirbsm/dealii,jperryhouts/dealii,andreamola/dealii,danshapero/dealii,angelrca/dealii,naliboff/dealii,andreamola/dealii,naliboff/dealii,naliboff/dealii,danshapero/dealii,gpitton/dealii,andreamola/dealii,JaeryunYim/dealii,spco/dealii,andreamola/dealii,EGP-CIG-REU/dealii,maieneuro/dealii,pesser/dealii,angelrca/dealii,spco/dealii,kalj/dealii,sairajat/dealii,spco/dealii,Arezou-gh/dealii,naliboff/dealii,jperryhouts/dealii,ESeNonFossiIo/dealii,danshapero/dealii,andreamola/dealii,angelrca/dealii,sairajat/dealii,nicolacavallini/dealii,gpitton/dealii,shakirbsm/dealii,JaeryunYim/dealii,pesser/dealii,andreamola/dealii,nicolacavallini/dealii,maieneuro/dealii,shakirbsm/dealii,naliboff/dealii,ESeNonFossiIo/dealii,jperryhouts/dealii,EGP-CIG-REU/dealii,jperryhouts/dealii,EGP-CIG-REU/dealii,Arezou-gh/dealii,spco/dealii,nicolacavallini/dealii,sairajat/dealii,EGP-CIG-REU/dealii,gpitton/dealii,Arezou-gh/dealii,ESeNonFossiIo/dealii,angelrca/dealii,andreamola/dealii,pesser/dealii,spco/dealii,danshapero/dealii,ESeNonFossiIo/dealii,JaeryunYim/dealii,maieneuro/dealii,sairajat/dealii,pesser/dealii,shakirbsm/dealii,sairajat/dealii,JaeryunYim/dealii,nicolacavallini/dealii,naliboff/dealii,gpitton/dealii