[petsc-users] ts_type euler

[Barry Smith]

On Nov 26, 2012, at 10:49 AM, Blaise A Bourdin <bourdin at lsu.edu> wrote:

> Hi,
> 
> I am working with a student on converting an existing code from hand-written ODE solver to a TS. In order to validate the port, we want to compare the results of the existing code with the same methods implemented in TS. When running the examples in src/ts/examples/tutorials, it seems that -ts_type euler doesn't work, and that the iterate is simply equal to the initial value. Try for example
> 	./ex17 -da_grid_x 40 -drawcontours -draw_pause .1 -ts_type euler
> in petsc-3.3
> 
> Are we missing something?

   ex17 is a DAE so euler won't work properly. Hence ex17 behaves badly as you report (yes, we should somehow have the code tell you this). 

   Other examples that are not DAEs should work for Euler, but the time-step may be so small you don't see much change without running for a very large number of time-steps 

   Barry

> 
> Blaise 
> 
> 
> 
> -- 
> Department of Mathematics and Center for Computation & Technology
> Louisiana State University, Baton Rouge, LA 70803, USA
> Tel. +1 (225) 578 1612, Fax  +1 (225) 578 4276 http://www.math.lsu.edu/~bourdin
> 
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