Help me to solve Do-loop for large matrices (Mathematica)

[kaizen.moto]

Hi all,

I have difficulties about applying the Do-loop command as it takes very long time to run (more than 24 hours and it keeps running).

However, if i do it manually, without Do command, i.e. putting the values of the variables, Mathematica gives me a pretty quick output.

Please see the attached files.

I really appreciate for any comments.


Thanks

 

[Bill Simpson]

When I evaluate the "Do loop" version I see errors

SetDelayed::write: Tag Times in Pi/a[m_] is Protected.
SetDelayed::write: Tag Times in Pi/a[n_] is Protected.
followed by a variety of other SetDelayed and Part errors.

That very likely indicates something is wrong and needs to be tracked down.

But given two notebooks over a hundred kilobytes each with a variety of changes in format and organization makes it very difficult to try to track down what is wrong.

It is unfortunate, but I don't believe there is a "diff" utility that understands Mathematica notebooks and can overlook meaningless differences while pointing out significant differences. I can manually find some of the things you have changed to turn one into the other but I have not been able to track down exactly what was broken in changing from the "manual" to the "do" version.

If this were mine I would track down and figure out and fix what was causing those errors. I would begin at the top of the two files and track down what changes you have made are important, what are not, and where errors have been introduced.

 

[Winzer]

Did you test this code in short segments to see if it even works?
Break it down section by section?

 

[kaizen.moto]

I have run and checked all the codes, segment by segment by breaking them into an indvidual cell, they are all working fine and give me the outputs without any errors or warning.

I don't have such errors displayed when I run the codes using version 7 (both windows and linux machines).

My problem is only that the Do-loop version takes such a very long time to run and still I don't have any output. I need some suggestions if there is any way to improve my codes or any modifications in the syntax/command that need to be replaced.

I welcome any comments and really appreciate it.

Thank you.

 

[alphy]

for reaching out for help with your Do-loop in Mathematica. I understand that it is taking a long time to run and you are looking for a more efficient solution.

One potential solution is to use the NestList or NestWhileList functions instead of a Do-loop. These functions allow you to iterate a function over a list of values and can often be faster than a Do-loop. Another option is to parallelize your code using the ParallelDo or ParallelTable commands, which can speed up the computation by utilizing multiple processors.

Additionally, you may want to consider breaking your large matrix into smaller chunks and using the Do-loop on each chunk separately. This can also help speed up the computation time.

I hope these suggestions help and that you are able to find a more efficient solution for your problem. Best of luck!