Stiff Delay Differential Equations

Does anybody know how to solve STIFF differential equations with delay in time? The solvers in Matlab (dde23,...) are for non-stiff DEs; they cannot be applied to stiff DEs with delay; I have tried all of them. Without delay, my problem can be solved using ode15s, ode23t, but not ode23, ode23tb. Thanks in advance

Answer 1

[Torsten]

radar5 is your friend:

http://www.unige.ch/~hairer/software.html

Best wishes

Torsten.

[Ismaeel]

Thanks Torsten for the reply. I have looked at the link and unfortunately, the code is written in Fortran language.

Answer 2

[Leo Sun]

Hi there, I have a problem solving stiff delay differential equations recently. I just found that there's a paper written by Vikas Agrawal's group and they used a solver called "dde15s" for there calculation.

We can find the paper at the following website: https://onlinelibrary.wiley.com/doi/10.1021/bp034226s

At the bottom of the website, click "Supporting Information", and download the zip file "bp034226ssi20030804_024052.zip", which the dde15s.m is inside (or you may download the attachment form this comment).

But I found a new problem. I try to use dde15s instead of dde23 in my code, then the error appears:

    Error using vertcat
Dimensions of matrices being concatenated are not consistent.

    Error in dde15s>solextend (line 155)
solout.idata.kvec = [sol.idata.kvec; solex.idata.kvec(2:end)];

    Error in dde15s (line 139)
      sol = solextend(sol,solex);

In dde15s.m, function "solextend" is for Concatenate two solution structures produced by ODE15S. And the Author said " This function works with ODE15S from MATLAB 6.5, but it may require modifications to work with other versions."

I think the error exist in my code because I use the Matlab 2017a version. So is there anyone can fix that error and make "dde15s.m" fit to the newest version of Matlab?

Thanks for all your help.