Error: The variable VAC in a parfor cannot be classified

Dear All,

I read some of the solutions to the error mentioned in the subject of this question but they all seemed vague to me. I have a code as follows:

VAC = zeros(taw_max ,2);
parpool ('local',12)
parfor taw = 0:1:taw_max
    taw_matrix = zeros(n-taw , 1);
    for t = 0:(n-1-taw)
        allmatrix = zeros (nt,1);
        for i=1:nt
            allmatrix (i,1) = mh * dot (s_t , s_t_taw )/dot(s_t , s_t); %where s_t . s_t_taw and mh are all defined values
        end
        taw_matrix (t+1 ,1) = sum(allmatrix);
    end
    VAC (taw +1 ,2) = mean (taw_matrix);
    VAC (taw +1 ,1) = taw ;
end

it seems that the parfor loop can not classify the VAC matrix so that I can not write the output of my calculations into the corresponding cell of the VAC matrix. Would you please help me with a solution to this matter?

Thank you so much

Answer 1

[Edric Ellis]

I think you simply need to ensure that you make only a single assignment into VAC, as the code analyzer message suggests. Like this:

    VAC(taw + 1, :) = [taw, mean(taw_matrix)];

[Ced]

Second that. For correctness, I think the order should be

VAC(taw + 1, :) = [taw, mean(taw_matrix)];

but that's a detail.

On a side-note, you cannot have a space between a function name (here "mean") and the parenthesis of the argument. Matlab will think that mean is a variable name.

PS: Thanks for correcting the indentation, much better ;)

[Homayoon]

Thank you so much Edric and Ced!

[Edric Ellis]

Fixed my answer to put the elements in the correct order - well spotted Ced!

Answer 2

[mohchali Alichina]

I have a function and I need to apply this function to an electrician field ( apply waveform to ion motion) . Kindly can anyone guide me to do it! thanks in advance

Fs=25.8e6;
%run swiftfunccycle10ms function
[y,swiftT] = swiftfunccycle10ms(100,10e3,300e3,67e3,80e3,20e3,67e3,80e3);
%------------------------------------
s=real(swiftT);
[cfs,frq] = cwt(s,Fs); %continues wavelet transform
tms = (0:numel(s)-1)/Fs;%length of s
figure
subplot(2,1,1)
plot(tms,s)
axis tight
title('swiftT Scalogram')
xlabel('Time (s)')
ylabel('Amplitude')
subplot(2,1,2)
surface(tms,frq,abs(cfs))
axis tight
shading flat
xlabel('Time (s)')
ylabel('Frequency (Hz)')
%set(gca,'yscale','log')
ylim([10000 500000]);
%---------------------------------------------
%run swiftfunccycle function
[y, signalT]=signalfunccycle(0.1,10000,300000,67000,80000,200000);
%---------------------------------------------
s=real(signalT);
[cfs,frq] = cwt(s,Fs); %continues wavelet transform
tms = (0:numel(s)-1)/Fs;%length of s
figure
subplot(2,1,1)
plot(tms,s)
axis tight
title('signalT Scalogram')
xlabel('Time (s)')
ylabel('Amplitude')
subplot(2,1,2)
surface(tms,frq,abs(cfs))
axis tight
shading flat
xlabel('Time (s)')
ylabel('Frequency (Hz)')
%set(gca,'yscale','log')
ylim([10000 500000])

[Walter Roberson]

Where you are using parfor that this might apply?

Your signalfunccycle and swiftfunccycle10ms are not found anywhere on the Internet that I can see, so we cannot test your code.