[petsc-users] SNES with constraint diverges

[Josh L]

Hi,

I am using SNES to solve an nonlinear equation f(u), and I know all the u_i
should be 0 and 1.

First, I use SNES without constraint, and it converges.

But, If I set
     SNESSetType(snes,SNESVINEWTONRSLS,ierr)
     SNESVISetVariableBounds(snes,xl,xu,ierr)

where xl and xu is vector, and xl_i=0 and xu_i=1

then SNES fails to converge, because linesearch fails(snes reason = -6),
and the norm of residual is not reducing(the norm of incremental solution
is reducing)

The reason to add constraint is that I want to implement some
irreversibility.


Thanks,
Josh