Going to previous step while debugging

Hi

How to go to previous step while debugging in matlab just like we use F10 for next step? Is there any such option?

Thanks - Lalan

Answer 1

[Guillaume]

You would think it would be something easy to implement in a interpreted language, but unfortunately, it's not possible to move the execution pointer to an arbitrary line in matlab.

You can only step forward I'm afraid.

[Walter Roberson]

One step back could require restoring a lot of state if going back was intended to mean "undo".

[Guillaume]

Well Visual Studio can do it in compiled languages. There is no state undo, just a repositioning of the EP. It's still incredibly useful when you want to replay something that didn't behave as you expected.

Admittedly, Visual Studio is the gold standard of programming environment, but I'm always disappointed by the limited editing and debugging facilities of matlab which only target one language.

[Walter Roberson]

I copy and paste sections of the line into the command window to figure out what was going on. Presuming that is that going back doesn't involve a change of control such as wanting to not terminate a loop that was just popped out of.

[Guillaume]

Actually, what I really miss is the ability to skip (as in not execute) a line.

I just came across this today debugging some code, arrived on a line which contained a typo (wrong variable name). I could just have typed the correct instruction in the command window and skipped to the next line instead of restarting the debugging from scratch.

It's the same concept though: give the user the ability to move the execution pointer around.

[Image Analyst]

This capability is called "edit and continue". I love it in Visual Studio and am frustrated it's not there in MATLAB. I use Walter's method of doing/undoing stuff in the command window while at a breakpoint.

Answer 2

[Robbin van Hoek]

Not sure if it will help you since i don't know why you need to go back, but have a look at conditional breakpoints. This helped me a lot in the cases where i wanted to go back one step in debugging.

[Lalan]

Thanks Hoek for the answer. I felt this necessity here. While debugging a program, I accidentally crossed a function where I needed to go inside that function. So I wanted to come back to previous step and step into that function.