Collaboration diagram for Linear solver:

Variables
integer, dimension(nvarmx), save	idircl

integer, dimension(nvarmx), save	ndircl
	number of Dirichlet BCs More...

Detailed Description

Variable Documentation

integer, dimension(nvarmx), save idircl

indicates whether the diagonal of the matrix should be slightly shifted or not if there is no Dirichlet boundary condition and if istat = 0.

0: false
1: true Indeed, in such a case, the matrix for the general advection/diffusion equation is singular. A slight shift in the diagonal will make it invertible again.
By default, idircl is set to 1 for all the unknowns, except $\overline{f}$ in v2f modelling, since its equation contains another diagonal term that ensures the regularity of the matrix.
Remarks
the code computes automatically for each variable the number of Dirichlet BCs

integer, dimension(nvarmx), save ndircl

number of Dirichlet BCs