[firedrake] Jacobian wrong with -snes_fd_color

[Buesing, Henrik]

So, the only way to deal with this is the following?

Use my functions to calculate the values pointwise. Then, provide the correct derivatives via the coefficient_derivatives keyword in the derivative() function.

Henrik


> 
> 
> Dear all,
> 
> I have a lot of coefficients in my form, e.g.
> 
> 1)  Calculate density rhow pointwise from temperature and pressure via
> interpolation of a table rhow = Function(DG1)
> rhow.dat.data[:]=calc_rhow(temp,Tsat,pw)
> 
> 2)  Averaging
> rhow_avg = (rhow('+') + rhow('-')) / 2.0
> 
> 3)  Use rhow_avg in my form.
> 
> This works all right for calulcating F(u), but fails when computing the
> Jacobian. Since I calculate things pointwise and providing all the
> derivatives is not so easy I use -snes_fd_color.
> 
> What I would want to happen is that the function calc_rhow is called
> every time rhow_avg is needed. This seems not to be the case. Rather the
> coefficient is assumed constant and thus the derivative is zero.
> 
> How can I make sure that the function calc_rhow is called every time I
> need rhow_avg?
> 
> Thank you!
> 
> Henrik
> 
> 
> 
> 
> 
> 
> --
> Dipl.-Math. Henrik Büsing
> Institute for Applied Geophysics and Geothermal Energy E.ON Energy
> Research Center RWTH Aachen University
> ------------------------------------------------------
> Mathieustr. 10            |    Tel +49 (0)241 80 49907
> 52074 Aachen, Germany     |    Fax +49 (0)241 80 49889
> ------------------------------------------------------
> http://www.eonerc.rwth-aachen.de/GGE
> hbuesing at eonerc.rwth-aachen.de
> ------------------------------------------------------
> 
> 
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