# [Getdp] Newton Raphson method with a time dependent problem

Olivier Castany castany at quatramaran.ens.fr
Tue Aug 3 20:30:04 CEST 2010

```Hello,

>         JacNL[ dlambdadT[{T}] * Dof{T} * {d T} , {d T} ]
>         [ lambda[{T}] * Dof{d T} , {d T} ]

This looks good.

> But I must confess I was surprised to see that you have also a "Dof" in the second line. I looked at the "MagnetoStaticsNonLinear<https://geuz.org/trac/getdp/wiki/MagnetoStaticsNonLinear>" example from the Wiki:
>
>       Galerkin { JacNL[ - dbdh[ {d phi} ] * Dof{d phi} , {d phi} ] ;
>                  In Steel ; Jacobian MyJac ; Integration MyInt ; }
>
>       Galerkin { [ b[ - {d phi} ] , {d phi} ]  ;
>                 In Steel ; Jacobian MyJac ; Integration MyInt ; }
>
> There is no Dof used for the non-JacNL part.
> The interesting thing is that in your example it is necessary to have it whereas in the Wiki example it does not work if I use Dof (by replacing "b[-{d phi}]" by "mu_Steel[SquNorm[{d phi }]] * Dof{d phi}").

Strange. Can you check with the opposite sign ?
Maybe you made a mistake with the sign.
We have : h = - Grad phi
so : b = mu * h = mu * (- Grad phi)

A+

```