Parfor --> Undefined function 'colon' for input arguments of type 'distributed'.

Hi,

I am new with the parallel toolbox and I need some help. I have a code that looks like this

function A = main_function(..)

parfor c1=1:m
        for c2=1:n
            if c2 >= c1
                A(c1,c2,:)= my_function(..);
            end
            end
            
        end
end

I get an error that says

Error using internal_compute_H_9int_vect_simplified (line 141). The source code (C:\Users\..\main_function.m) for the parfor-loop that is trying to execute on the worker could not be found.

Caused by:

Undefined function 'colon' for input arguments of type 'distributed'.

Error using remoteParallelFunction (line 84)

Worker unable to find file.

Undefined function 'colon' for input arguments of type 'distributed'.

At first I thought that the problem was the ":" in the matrix A, but then I tried this simple code

m = 3;
n = 3; 
H = zeros(2,2,3);
 beta =rand(3,1);
    parfor c1=1:m
        for c2=1:n
            H(c1,c2,:) = 3*rand(3,1);
        end
    end

and it works.

What is the problem? Is related to the location of the function "main_function", to the matrix A , or to what I do in the funtion "my_function" ? What "distributed" actually means here?

Best

[Raymond Norris]

You might need to post what's being passed to my_function. And can you attach my_function as well?

[Maria]

Hi Raymond!

Unfortunately, I am not allowed to share the code, but I can provide the class of the data used and a small example. I hope it helps for the debugging of the error.

In the main , I have:

H = internal_compute_H(sup1,sup2,dir_curr1,dir_curr2,w1,w2,ori1,ori2,1,beta,TOL);

All the inputs are double, either matrices or vectors (sup1/2 have size 728 X 12, dir_curr, w and ori have size 728 X 1, beta has size 1 X 25) .

The function looks like below

function H_result = internal_compute_H(sup1,sup2,dir_curr1,dir_curr2,w1,w2,ori1,ori2,1,beta,TOL)
m = length(w1);
n = length(w2);
LENGTH_BETA = length(beta);

% organize sliced variable for code optimization (parallelization)

xm_1 = zeros(1,m);
ym_1 = zeros(1,m);
zm_1 = zeros(1,m);

xm_2 = zeros(1,m);
ym_2 = zeros(1,m);
zm_2 = zeros(1,m);

% to allow a perfomed used of sliced arrays (paralellization)
temp_sup1_xm = sup1(:,1:3:12);
temp_sup1_ym = sup1(:,2:3:12);
temp_sup1_zm = sup1(:,3:3:12);

parfor c1 = 1 : m
    xm_1(c1) = min(temp_sup1_xm(c1,:)); %min(sup1(c1,1:3:12));
    ym_1(c1) = min(temp_sup1_ym(c1,:));%min(sup1(c1,2:3:12));
    zm_1(c1) = min(temp_sup1_zm(c1,:));%min(sup1(c1,3:3:12));
end

parfor c1 = 1 : m
    xm_2(c1) = max(temp_sup1_xm(c1,:));%max(sup1(c1,1:3:12));
    ym_2(c1) = max(temp_sup1_ym(c1,:)); %max(sup1(c1,2:3:12));
    zm_2(c1) = max(temp_sup1_zm(c1,:)); %max(sup1(c1,3:3:12));
end

clear temp_sup1_xm temp_sup1_ym temp_sup1_zm
xn_1 = zeros(1,n);
yn_1 = zeros(1,n);
zn_1 = zeros(1,n);

xn_2 = zeros(1,n);
yn_2 = zeros(1,n);
zn_2 = zeros(1,n);

% to allow a perfomed used of sliced arrays (paralellization)
temp_sup2_xm = sup2(:,1:3:12);
temp_sup2_ym = sup2(:,2:3:12);
temp_sup2_zm = sup2(:,3:3:12);

xn_1 = xm_1;
yn_1 = ym_1;
zn_1 = zm_1;
xn_2 = xm_2;
yn_2 = ym_2;
zn_2 = zm_2;

clear temp_sup2_xm temp_sup2_ym temp_sup2_zm

parfor c1=1:m
        for c2=1:n
            if c2 >= c1             
                if dir_curr1(c1)==dir_curr2(c2)
                    
                    if ori1(c1)==1
                               H_result = my_function(zm_1(c1),zm_2(c1),zn_1(c2),zn_2(c2), ym_1(c1),ym_2(c1),yn_1(c2),yn_2(c2), xm_1(c1),xm_2(c1),xn_1(c2),xn_2(c2),beta,TOL);
                    end
                end
            end
        end
end

The error that I get tells that the "internal_compute_H" could not be found, Caused by: Undefined function 'colon' for input arguments of type 'distributed'. Error using remoteParallelFunction (line 84). Worker unable to find file. Undefined function 'colon' for input arguments of type 'distributed'.

[Maria]

Maybe it can help, I already tested "my_function" in a different (parallelized) code and it did not give any error. This is why I am a bit confused.

Answer 1

[Maria]

So, I had a problem in my code, that is now fixed. I had another function, which I forgot to test, and where I was using distributed arrays. I removed the 'distributed' and now it works! Strange that the error did not point exactly at that function...but now it works!