I need help to correct this code. How do I 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.)?

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

[Bob Thompson]

What's wrong with it? Please provide more details, including a complete error message, if available.

[Raymond Awoyemi]

O n running the code, this particular line detPhotonsF = F + randn(noOfRuns,1)* stD2;

is returning error: Incorrect dimensions for matrix multiplication. Check that the number of columns in the first matrix matches the number of rows in the second matrix.

Answer 1

[Bob Thompson]

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