Spatial source for diffusion equation

Hi all, I would like to solve a diffusion equation -d^2n/dx^2 = S(x) in 1D between -L < x < +L, with a spatial source term, for instance "1" between -0.1L < x < 0.1L and 0 elsewhere. I'm a bit confused by the structure of pdepe. And I can't find an example with a source term.

Can anybody help me ?

Thanks a lot

Stéphane

Answer 1

[Torsten]

Just take pencil and paper and integrate n''(x)=S(x) twice with respect to x.

If you don't succeed, use bvp4c instead of pdepe since your equation is stationary.

Best wishes

Torsten.

[Stéphane]

Thanks a lot for your advice on bvp4c.

I can't see how a pencil will help me for learning matlab syntax of pdepe... Should I use it for pressing the keys on the keyboard ?

Best wishes

Stéphane

[Torsten]

I don't know if the equation you have in mind is more complex than the one you wrote above. But integrating a piecewise constant function (S(x)) twice is a task I usually accompish without computer support.

Best wishes

Torsten.