y = bd'; x_test = min(br)-500:max(br)+500;
A = [(br'.^2), br',ones(length(br)',1)]; the error is here
w = A\y;
A_test= [x_test'.^2,x_test',ones(length(x_test)',1)]; y_test =A_test*w;
(I'm trying to fit a 2nd order linear regression model to a set of data)
How do I fix the error?
br is a column vector. If I remove the transposes on the first two, I get another error- matrix dimensions don't agree in w=A\y. br is 65x1 and y is 1x65.
For A, the first column should contain the squares of the elements in br. The 2nd- just the elements in br. The 3rd- ones.
When I did this, the ‘A’ assignment did not throw any error:
br = 1:10; A = [(br'.^2), br',ones(length(br)',1)];
My guess is that you transposed ‘br’ to a column vector somewhere else.
Just before the ‘A’ assignment, put:
sbr = size(br)
and see what the dimensions of ‘br’ are.