# MATLAB: Running only a certain section of an m-file

• MATLAB

## Main Question or Discussion Point

Hi

I have an m-file which accesses another m-file at some point, but I don't want it to run the entire file. Is there a way to skip the first and last 10 lines of the file?
I could just create a new file with the code I need, but this is like an addon to a programme, so if I could leave the original untouched that would be best.
Hope that makes sense. Any advice much appreciated!
Thanks.

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Dr Transport
Gold Member
put a % sign at the beginning of the lines you wish to skip....

Yes, that would work, but again I would be changing the original file which I'm trying to avoid. Is there something like a "goto" command or similar?

MATLABdude
Yes, that would work, but again I would be changing the original file which I'm trying to avoid. Is there something like a "goto" command or similar?
No. Why not just copy and paste the pertinent code section into a new m-file? You wouldn't be modifying the original in that case.

EDIT: Or you can copy the entire file and then comment out the first and last sections. Really, the beauty of MATLAB is that you don't need to be constantly recompiling and regenerating binaries. Stuff just happens on the fly.

Think that's what I'll do. I'm creating an addon to an existing piece of code, so ideally people could update that original m-file and my addon would still work fine.
As I am going to create a copy of the original code, 2 m-files will now have to be updated in order for my addon to work.
Doesn't really matter though.

MATLABdude
I suppose another thing you could do is to put in some if statements around the pertinent code blocks. If the m-file is a function, you can put in an extra input (and either look at the input or use the nargin function)

Code:
if nargin > 3  %(or maybe something like variable3=='DEBUG')
...
end
If the m-file is just a code block, with no input or outputs, you can do the same thing using something like, say,

Code:
if switchVariable==TRUE
...
end
Code:
if exist debugVariable %define debugVariable when needed
...
end
More on the exist function:
http://www.mathworks.com/access/helpdesk/help/techdoc/ref/exist.html

That or to strip out the parts at the beginning and end and put them into another m-file which is called only when you need them.