How to use parfor for fast matrix calculations with different dimensions???

Here is the code that i wrote to find 1 in the matrix with general for-loop:

b=[0 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0 0 0 0 0; 0 0 0 1 1 0 0 0 0 0; 0 0 1 1 1 1 1 0 0 0; 0 0 0 1 1 1 0 0 0 0; 0 0 0 1 1 0 0 0 0 0; 0 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0 0 0 0 0]; n=0; s=size(b,1); %rows t=size(b,2); %columns v = zeros(s*t,2); for g=1:s for h=1:t if b(g,h)== 1 n=n+1; v(n,:)=[g h;]; end end end v v=(v(v~=0))

here are 2 problems:

a) i can't use the counter 'n', so i made a formula n=col+(row-1)*col. However parfor doesn't allow me to use the index from the earlier loop :O :( please tell me how should i use the parfor to search position of the 1!!! :(

b) i want the final v matrix without zero i.e. with the values other than 0 only. v=(v(v~=0)) works and gives the v matrix in a column matrix. that is not what i want. :(

Please Help!

Answer 1

[Thomas]

You do not need to use 'parfor' or even 'for' to get to what you are trying (i.e. find 1's in the matrix). Is there a specific requirement to use 'parfor' or 'for'?

this single line of code does everything your code does and I'm sure is faster than a parfor..

 [row,col]=find(b==1);
 out=[row col] % is you want it as a matrix

If you definitely want to use parfor try reading the Reduction Assignments: http://www.mathworks.com/help/distcomp/getting-started-with-parfor.html#brdqn6p-1

Answer 2

[Mandar]

Actually i have wrote down something like this to search for a color reference in live feed from webcam:

opengl hardware while (nFrame<z)

    b = step(vidobj);
    n=0;
    yb=size(b,1); %rows
    zb=size(b,2); %columns
    %u=zeros(zb,2); %------------------------------

    v=0;
    for g=1:1:yb
        for h=1:1:zb
            if (b(g,h,1)>=rot_min) && (b(g,h,1)<=rot_max)
            n=n+1;
            v(n,1)=g;
            v(n,2)=h;
            end
        end
    end
v;
%end of rot search

so now i want to exploit the core i5 to use all for cores and make the code even more faster...