Is not possible to install Mathematica 8 and Mathematica 9 on the same computer?

Hello Intan,

I took a bit of a look at the notebook. Nothing seems explicitly wrong with its code after a relatively quick glance. But since the code takes a long time to run, I cannot run the example much to see the errors being generated on my computer (and I do have a copy of Mathematica version 8, but again, since the run time is long I cannot run it to compare). The error messages that are being returned (which are in your saved notebook) suggest that NDSolve stopped being able to solve at values around 30 (in the first error message case). Hence the possible reason for the subsequent errors involving InterpolationFunciton being evaluated for values larger than that. If there is a pared down version of the notebook that runs quicker but which still exhibits the problems then I could do comparison runs on both versions of Mathematica.

One thing you might do is to work with options to NDSolve to see if explicitly choosing solving methods adjusts the behavior. But, again, having a more quickly running example to play with in the processing of debugging will help you considerably.

Perhaps someone here with greater insight into NDSolve intricacies can chime in...

The notifications "Continue with updated styling" etc,... have to do with which version of the Default.nb StyleSheet Mathematica 9+ uses when opening notebooks from version 8 and earlier. It does not have anything to do with general execution of code from earlier versions. So this is not the issue that you are encountering. The issue presumably has to do with the code itself. But one would need details on the code as well as what you mean by "can't run the script properly". The devil is in the details. Provide them and perhaps the denizens of this forum can ferret out the issue for you.

Memory might be an issue of course, given that your friend's code is taking so long to run. One can often rewrite code to keep track and report on memory usage using functions like MemoryInUse[], etc... And also presumably you can keep an eye on the Mathematica Kernel's memory usage through Windows tools (but I don't know which as I am a Mac user).