How to do linear regression?
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How to do a regression line ?
1 个评论
Stephan
2018-8-22
Do you have access to Optimization Toolbox or to Curve Fitting Toolbox?
回答（2 个）
Star Strider
2018-8-22
1 个投票
5 个评论
Stephan
2018-8-22
Note that this solution only gives a correct answer, when the function passes through the origin of the coordinate system
y= m .* x + n ---> with n = 0
will give a correct answer. If n~=0 you get more bad results for m the more n is different from zero.
Star Strider
2018-8-22
It gives a correct result if you include a column vector of ones with the independent variable to estimate the intercept:
B = [x(:) ones(size(x(:)))] \ y(:); % Estimate Parameters
yfit = [x(:) ones(size(x(:)))] * B; % Calculate Regression Line
figure
plot(x, y, 'pg')
hold on
plot(x, yfit, '-r')
hold off
grid
Stephan
2018-8-22
Nice,
and learned something again ;-)
Star Strider
2018-8-22
Thank you!
Actually, I got the idea for the column of ones from the documentation for the regress (link) function when I first began using it, many years ago. (I simply forgot to include polyfit and friends initially.)
Stephan
2018-8-22
I had to think about it for a few minutes. But after understanding what happens, i saw that this is a pretty nice approach.
Image Analyst
2018-8-22
0 个投票
See my attached demo.
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2018-8-22
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