convergence monitoring

[Andreas Grassl]

Hello,

I want to monitor the convergence of the KSP-solver, i.e. plot the number of
iterations vs. the error/residual norm.

I discovered the options -ksp_monitor_draw_true_residual and
-ksp_monitor_true_residual.

Now the questions: What does the grafical output of
-ksp_monitor_draw_true_residual represent? I see the iteration count at the
x-axis and expected the norm of the residual at the y-axis, and some scaled
value at the y-axis. Is this the logarithm of the residual/which residual?

If I output to .ps, I get overlayed the steps and don't see anything useful at
the end. Is there a way to extract only the last picture?

Is there an easy (without hacking the PETSc sources) way to output a customized
convergence monitoring line like -ksp_monitor_true_residual at every step?

Cheers,

ando

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