'step size too small' when solving with 'pdenonlin' even when the initial guess of solution is almost excatly the solution!

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Mohammad Monfared 2014-4-13

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https://ww2.mathworks.cn/matlabcentral/answers/125597-step-size-too-small-when-solving-with-pdenonlin-even-when-the-initial-guess-of-solution-is-almos

评论： Sravan Kumar Putta 2021-1-7

Hi,

I'm trying to solve an elliptic PDE using 'pdenonlin' function. I can get the solution in 1-D by another approach but when I simplify the main 2-D problem into 1-D to provide the 'pdenonlin' with a suitable initial guess, the 'step size too small' message is displayed.

Jacobian is calculated by 'full' method. Returned residual at iteration zero is '0.00049' but there isn't any improvement to it by 'pdenonlin'. Changing mesh size didn't help either.

Why this is happening? I really need some insight into this issue.

thanks,