How to automatically choose to compute for or parfor loops

Hi,

I wonder if there's a way to specify if I want to compute with a normal for or with a parfor.

What I don't want is to make a switch with two cases (case 1 --> parfor; case2 --> for;) because what's inside the loop is quite long so I don't want to copy/paste so many code lines and it's not 100% necessary to make this choice automatic. But sometimes I have to calculate few inputs and sometimes a lot of them.

EDIT: I guess I can make two functions: 1 for looped and another parfor looped, but is there any other option?

Answer 1

[Sean de Wolski]

You can use this syntax for parfor

parfor (loopvar = initval:endval, M); statements; end

Where M is dynamically determined. If it's zero, then this loop will run serially.

[Felix Lauwaert]

Will it avoid matlab start a parpool? The problem is that I don't want to wait a parpool to start everytime I want to make some small checks with my code but I need parfor when I'm going to run day-long code, but I don't want to be changing all the time "for" and "parfor".

[Sean de Wolski]

No, it does not:

parfor (ii = 1:10,0),disp(ii),end

[Sean de Wolski]

Also, you can turn off the auto start of the pool in preferences so it never starts without you explicitly telling it to.

And, if startup is the cost you don't want to wait for, consider boosting the idle timeout to longer and just keep the pool open.

[Felix Lauwaert]

OK, thanks!