[petsc-users] How to create symmetric matrix?

[Faraz Hussain]

I am learning petsc and using the following code to insert values into my matrix:
ierr = MatSetValue(A, row, col, value,INSERT_VALUES);
ierr = MatSetValue(A, col, row, value,INSERT_VALUES);

Since my matrix is symmetric, I want to speed things up only calling MatSetValue once. I tried setting: 

 ierr = MatSetOption(A,MAT_SYMMETRIC,PETSC_TRUE);

However, whenver I solve Ax=b, I get a wrong solution for x ( almost all zeroes ).  I am guessing MAT_SYMMETRIC is not automatically creating the lower triangular matrix from the upper triangular matrix?


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