Assignment has more non-singleton rhs dimensions than non-singleton subscripts error

Hi everyone, I am running this for loop and I am getting the next message :Assignment has more non-singleton rhs dimensions than non-singleton subscripts. Could someone explain to me why? The goal in this exercise is to compute the H/V ratio for an incequake time series with a dimnesion of 721x6000.Thank you!!

mat1=zeros(721:length(EHV))
for i=1:length(ETB21)
    EHV=(((ETB21N).^2)+((ETB21E).^2))/(((ETB21N).^2)+((ETB21E).^2)+((ETB21).^2));
    mat1(i,:)=EHV
end
HVmn=mean(mat1,1);
plot(HVmn)

Answer 1

[Walter Roberson]

mat1 = zeros(721, length(EHV));

Notice the comma instead of colon.