PARFOR error not enough input arguments

Hi, When I try a simple following code

> parfor i=1:2000

> j=i;

> end

I keep receiving this error:

> Error using parallel_function (line 589) Not enough input arguments.

I already ran > matlabpool open

Do you have any idea? Thanks!

[Walter Roberson]

Try using different variable names, such as ii and jj. I'm wondering if the problem has to do with the fact that "i" and "j" are by default defined as functions.

[Matt J]

No. I can run the code example without any errors. There's something in the bigger picture that's causing problems, I'd have to say.

Answer 1

[Matt J]

Does the problem presist if you close, then re-open matlabpool? Maybe it was just a temporary system problem.

Answer 2

[Image Analyst]

Look to me that the problem is not what you said, especially since Matt J said that he has no problem with just that small snippet you supplied. Looking at your error message: " parallel_function (line 589)" it appears that you've drastically simplified the code. While that is good in most instances, it looks like you've unfortunately removed the actual part of the code that caused the problem. To me, it looks like down around line 589 of your program you attempted to call the code you posted. The code you posted was actually in a custom function your wrote called "parallel_function" and it took some arguments and you didn't supply all the necessary input arguments. A big clue was the message "Not enough input arguments." So you may have defined the function this way:

function [out1 out2] = parallel_function(in1, in2, in3)

but you called it like this at line 589 (didn't supply the in3 argument):

[main_out1, main_out2] = parallel_function(main_in1, main_in2); % Line 589

Is that the reason?

[Matt J]

No, parallel_function is a stock function in the Parallel Computing Toolbox and somehow serves as the engine of PARFOR. Some internal problem had to have caused it to go haywire,

function varargout = parallel_function(range, F, consume, supply, ...
                                       reduce, identity, concat, empty, ...
                                       M, divide, next_divide)
%PARALLEL_FUNCTION
%   This is the basis of parfor, but is not officially supported, either with
%   this name or API.

%   Copyright 1984-2009 The MathWorks, Inc.
%   $Revision $ $Date: 2011/10/22 22:05:31 $

% The following is a help-style description of parallel_function.

[Image Analyst]

Thanks for the clarification. I don't have that toolbox so I didn't know.

Answer 3

[Masoud]

Thank you all for the answers/comments. Matt, you're right. I closed and re-opened everything and it's working now :)