Classification in Parfor Loops

parfor xIndex=1:2:c

          for yIndex=1:2:c
            x = xvec(xIndex);
            y = yvec(yIndex);
            M(xIndex, yIndex) = EscapeVelocity(-0.123+0.745*1i, x+y*1i,  m);
          end
end

MatLab says "The variable M in a parfor cannot be classified"

I would appreciate any explanation of why this occurs and how to correct it.

[Walter Roberson]

Can your EscapeVelocity routine be rewritten to be vectorized, passing in an entire vector of y values at once?

[Edwin]

Yes it can easily, I think.

Answer 1

[Walter Roberson]

Try constructing

xvec2 = xvec(1:2:c);
nxvec2 = length(xvec2);

yvec2 = yvec(1:2:c);
nyvec2 = length(yvec2);

M2 = zeros(nxvec2, nyvec2);

Then

parfor for xindex = 1 : nxvec2
  x = xvec2(xindex);
  for yindex = 1 : nyvec2
    y = yvec2(yindex);
    M2(xIndex, yIndex) = EscapeVelocity(-0.123+0.745*1i, x+y*1i,  m);
  end
end

Then

M(1:2:c, 1:2:c) = M2;

[Edwin]

As xvec and yvec were the same I have just made a general xvec. Selected parts of Code now read xvec2 = xvec(1:2:c);

n1 = length(xvec2);

M2 = zeros(n1, n1);

parfor xIndex=1:n1

          for yIndex=1:n1
            x = xvec2(xIndex);
            y = xvec2(yIndex);
            M2(2*xIndex-1, 2*yIndex-1) = EscapeVelocity2(-0.123+0.745*1i, x+y*1i,  m);
          end
end

[Edwin]

Got rid of the 2 and -1, they were from trying to mold your code to my uses. Thank you very much for your time.