[petsc-users] Can I use the direct solver without providing the analytical Jacobian?

[Rebecca Xuefei Yuan]

Hi,

If the nonlinear system is evaluated at F(u) = 0 in "FormFunction()",  
but the symbolic Jacobian is not provided. Is there any options that I  
can call to solve the corresponding linear system by direct solver?

Thanks very much!

Best regards,

Rebecca