Error： In an assignment A(I) = B, the number of elements in B and I must be the same.

This is my code

BF=initialBF();           %is a function returns a column vector BF(4,1)

..........

COmax = HRmax*SV;                                %ml/min

BF(3) =0.012*COmax;                              %ml/min

However, the error returns here, but this used to work until I add some other while function at its behind. I don't know wether it's related. I am confused now. Appreciate for the help.

[Walter Roberson]

What is size(HRmax), size(SV) ?