Problem with Linear System
 

Hello to everyone,

I am modeling unsteady flow in prismatic open channel with St Venant equations and implicit finite difference scheme.

Trying to solve the linear system of equations with direct method I receive the message:
Matrix is singular, close to singular or badly scaled.

I know that the inversion of the matrix is impossible to be done due to ill-conditioning of matrix.


How can I solve this problem?


Thank you.