MATLAB: I need help to correct this code. How to get this error corected (Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix.)

meansngstdev

function [SNRF, SNRUV] = SNG(noOfRuns)
NoOfPhotons = 1000000;
Q = 0.6;
b = 1;
E = 10000;
c = 0.00001;
stD = 1000;
Mean = 1000000;
for i = 1:noOfRuns
extPhotons = NoOfPhotons + randn(noOfRuns,1) * stD;
F = 0.01*extPhotons*2.303*E*b*c*Q;
stD2 = sqrt(F);
detPhotonsF = F + randn(noOfRuns,1)* stD2;
mean_detPhotonsF = mean(detPhotonsF);
stdev = std(detPhotonsF);
SNGF (i) = mean_detPhotonsF/stdev
end

Best Answer

I believe the error is in using matrix multiplication, versus element multiplication. You have:
detPhotonsF = F + randn(noOfRuns,1)* stD2;
which is causing the code to try and multiply the matrix of randn(noOfRuns,1) by the matrix of stD2. I'm assuming you want to multiply the corresponding elements, which would be the following:
detPhotonsF = F + randn(noOfRuns,1) .* stD2; % Using .* or ./ or .^ conducts elementwise operations
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