Creating values to a matrix with "if" statement

I have a .csv file which includes two columns and each column has matrix 68x1. in order to read the file I use these commands : clc clear filename1= 'myfile.csv' [d1,tex]= xlsread(filename1); b=d1(:,1); I would like to take some values using the command "if" I have written : if b<=4.5&&b<60 X=2*b+5 elseif b>=60 X=3*b-6 end

but it's no use. Could anyone help me please?