Linear approximation that goes through zero

Hello, I have a few points, and I need to approximate them with linear function that goes through zero. Any ideas?) Thank you in advance)

[Mathieu NOE]

HI

have you tried with 1st order polynomial (using polyfit) ?

[Image Analyst]

@Mathieu NOE I was going to suggest the way Matt did it

x=0:5 + 3;
y = 1.5 * x + randn(size(x)) * 0.4 + 10;
slope = x(:) \ y(:);
yFitted = slope * x;
plot(x,y,'.',x,yFitted, 'MarkerSize', 20);
grid on;

Is there a way to get the offset to be zero with polyfit()?

[Mathieu NOE]

@Image Analyst

seems the topic has been already debated quite often

How do I constrain a fitted curve through specific points like the origin in MATLAB? - (mathworks.com)

solutions from FEX :

polyfitZero - File Exchange - MATLAB Central (mathworks.com)

polyfit0.m - File Exchange - MATLAB Central (mathworks.com)

Answer 1

[Matt J]

Here's a simple example.

x=-5:5;
y=2*x+randn(size(x))*0.4;

slope=x(:)\y(:);
yapprox=slope*x;

plot(x,y,'o',x,yapprox);