Error using * inner matrix dimensions must agree

I have written a function in which one line is B = A*i; where A is a matrix and i is a scalar quantity.

i am calling this function many times around 4000 and the problem is for some time this statement is executing properly and after some time this error is showing at this line i do not know why. One more thing is that the function is executing different number of times when i am running it again and again.

Thank you.

Answer 1

[James Tursa]

Most likely i is not a scalar, hence the error. Try stopping on the error and then examining the dimensions to see what is going on.

dbstop if error
% then run your code

[Subham Burnwal]

Now In the workspace it is showing i as an empty matrix at the break point. How can i remove this error now.? i want to use i as a scalar. Thank You.

[James Tursa]

Look upstream in your code. Where do you define i? You must be defining it somewhere otherwise i would default to the inbuilt imaginary unit.

Answer 2

[Star Strider]

If ‘i’ is always a scalar, it should’t be throwing that error. Add this line before the ‘B’ assignment:

if sum(size(i)) ~= 2
    fprintf(['\n\ti = ' repmat('%f  ', 1, length(i)) '\n'], i)
end
B = A*i;

That will tell you if ‘i’ has somehow become a vector.