AZ_calc_blk_diag_inv: ERROR: the factorization has produced a singular U with U being exactly zero.
I am running a 3D TOUGH3 model with EOS7C and the AZTEC parallel iterative solver. Occasionally I receive this error that ends my model run, and the OUTPUT file gives me no clues as to what is going on to cause this.
Has anyone had experience with this and can help me understand what is causing this and/or how to resolve it?
"AZ_calc_blk_diag_inv: ERROR: the factorization has produced a singular U with U being exactly zero."
This may indicate a bad linear equation system (such as diagonal terms are all zero) formed during solving non-linear equations . It is difficult to tell the specific reasons. However, it may be avoided by slight changes of model parameters, such as time step size, convergence criteria and others, or even using different linear solver, or restart with the most updated SAVE.