For loop is printing the wrong size matrix.

I have a matrix of length 9 called average_BMI with the body mass index from 9 different college football teams. The first column of the matrix represents the average BMI of football players from the University of Michigan. I would like to compute the delta BMI by finding the difference between all of the other schools (columns 2-9 of average_BMI) and the average for Michigan. I have written the following for loop to do this.

MI = average_BMI(:,1)

for i = (2:9)
    delta_BMI(i) = MI - average_BMI(:,i)
end

However, each time I run this the output matrix has length 9 instead of 8 and starts with 0. Meaning it's not referencing the second column, but instead is finding the difference between Michigan and itself before calculating the rest. Am I inputting the information into the for loop wrong?

Answer 1

[Matt J]

 for i = (2:9)
    delta_BMI(:,i-1) = MI - average_BMI(:,i)
 end

However, if your original version worked threw no error messages, it means your average_BMI variable is really a vector, and the calculation requires nothing more than,

   delta_BMI= average_BMI(1) - average_BMI(2:9)

[Sarah Brehm]

Thank you so much!