Question: Does Maple 2020 support parallelisation using the Grid package?

 I recently tried using Maple 2020 to run example code for the Grid package provided in Section 15.8 of the Maple Programming Guide. Unfortunately, none of the sample code appears to work as advertised.

Firstly, when I try to run the first sequential Mandelbrot example provided, I get the following error:

Error, (in Mandelbrot:-MandelLoop) `break` outside of loop

This was easily fixed by replacing the break statement in the while with a boolean value flag, while k < iter and flag do (see attached image). With this minor change to the example provided in the manual, I was able to get the code sequential code to run in 45.743 seconds on a quad core laptop. The modifications to the sample code are highlighted in red below.

 MandelLoop := proc( X, Y, imageArray, i_low, i_high, j_low, j_high, iter, bailout )
        local flag, i, j, Xc, Yc, Xtemp, Ytemp, Xold, Yold, k, t;
        option hfloat;

        for i from i_low to i_high do
           for j from j_low to j_high do
               Xtemp := X[i];
               Ytemp := Y[j];
               Xc := Xtemp;
               Yc := Ytemp;
               k := 0;
               flag := true:
               while k < iter and flag do
                   Xold := Xtemp;
                   Yold := Ytemp;
                   Xtemp := Xold^2-Yold^2+Xc;
                   Ytemp := 2*Xold*Yold+Yc;
                   t := Xtemp^2+Ytemp^2;
                   if Xtemp^2+Ytemp^2 >= bailout then
                        imageArray[i, j, 1] := k - ln( ln( t ) )/ln(2.);
                        imageArray[i, j, 2] := imageArray[i, j, 1];
                        imageArray[i, j, 3] := imageArray[i, j, 1];
                        #break;
                        flag := false:
                  end if;
                  k := k+1;
               end do
           end do;
        end do;
    end proc:

The second, and seemingly more serious problem occurred when I tried to run the code in the last example that uses the Client/Server model to parallelise the Mandelbrot calculation. The code provided in the Programming Guide once again gives the break outside of loop error. However, after replacing the break statement in the Computeline procedure with a boolean flag as above, I found the code runs but does not enter either the Server procedure or the Computeline procedure that is actually supposed to do the work. This can be verified by including print statements in the Computeline or Server procedures. The parallelised code ran in less than one second, compared to 45 seconds for the sequential code. Unfortunately this was not due to a 45-fold speed up on my quad core laptop, but the fact that the code using the code parallelised using Grid Package did nothing whatsoever.

I have sent a number of e-mail requests to Maple Support asking them to explain these apparent errors and so far have received no response.

Any solutions to these problems from the Maple user community would be much appreciated.

Thanks.

John