gistfile1.matlab

    sum0=0;
    sum1=0;
   
    for i=1:m,
        sum0=sum0+(theta(1)+theta(2)*X(i,2))-y(i);
        sum1=sum0*X(i,2);
    end
 
    temp0=theta(1)-(alpha/m)*sum0;
    temp1=theta(2)-(alpha/m)*sum1;
 
   
    theta(1)=temp0;
    theta(2)=temp1;