How to fix index in a parfoor loop?

I have the following code and get indexing error

parfor dt=0:round(tmax/step)
  fprintf(1,'\b\b\b\b\b%05.2f',dt);
  for dm=0:dt
     A(dm+1,dt+1) = f(dm,dt);
  end
end

It does not make sense, for me, because each loop of the first for is stand alone in the variable dt. The size of A has been prefixed.

The error messages on the script are:

-The PARFOOR loop cannot run due to the way varaiable 'A' is used. (On line 1)

-Valid indices for 'A' are resticted in PARFOR loops. (On line 4)

Error when run:

Error: The variable A in a parfor cannot be classified. See Parallel for Loops in MATLAB, "Overview".

[Stephen23]

What is f ? And how big is it?

[Andreu Angles Castillo]

f is a function of two variables, input two variables and gives a scalar.

[Stephen23]

@Andreu Angles Castillo: please give the complete error message. This means all of the red text.

[Andreu Angles Castillo]

errors uploaded

Answer 1

[Titus Edelhofer]

Hi Andreu,

agreed, it looks as if this case could be handled. But it is fairly easy to work around this by separating the inner loop from the parfor loop:

n = round(tmax/step) + 1;
parfor dt=0:round(tmax/step)
  fprintf(1,'\b\b\b\b\b%05.2f',dt);
  col = zeros(n, 1);
  for dm=0:dt
      col(dm+1) = f(dm, dt);
  end
  A(:, dt+1) = col;
end

Titus

[Andreu Angles Castillo]

Thank you very much, it worked for me.