i have two curves how to find relation between two curves in matlab. that is If I have two curve A and B. I need to find a relation such that A=XB. what is X value?

i have two curves how to find relation between two curves in matlab. that is If I have two curve A and B. I need to find a relation such that A=XB.

[Lokesh Katari]

Assume these are my curves. I need to find relation between these curves

Answer 1

[Image Analyst]

How about this:

t = 1 : 10;
A = t .^ 2 + 20
B = 2 * A - 10;
plot(t, A, 'b-');
hold on;
plot(t, B, 'r-');
grid on;
legend('A', 'B');
X = A ./ B
% Check it:
X .* B

This isn't your homework is it?

[Stephen23]

"I already two curves A and B and X is common for them but you were doing A= t^2+20? Can you please explain clearly"

You have some curves A and B, but you did not give us these curves (as numeric data).

Image Analyst wrote some code that needs A and B to run, therefore Image Analyst invented some curves A and B (because you did not give us that data). Otherwise Image Analyst could not test their code.

When you use their code, you would use your own A and B curves.

[Lokesh Katari]

Okay let me put this way. My X should be a constant 1x1 value instead of vector. Is there any way to do this

[Stephen23]

"Okay let me put this way. My X should be a constant 1x1 value instead of vector. Is there any way to do this"

There is no scalar X that will exactly scale B onto A as shown in your example here.

Do you want a "best fit" of some kind? if so, what metric do you want as a measure of best fit?

[Lokesh Katari]

thanks for your time.

Assume my A curve is physical test data and B curve is software data. So can you take this way like what is best fit that B curve should become A curve, like what is the offset between these two curves

Correct If I am wrong in asking as I am new to Matlab

[Stephen23]

"...like what is the offset between these two curves"

In your question and previous comment you specified that you want some kind of scaling factor X.

Now you write that you want the "offset" between the two curves.

Which do you want: an offset or a scaling factor?

Note that in general neither of these will fullfile your requirement "that B curve should become A curve".

[Image Analyst]

If you just want the mean scalar to scale it you can do

factor = mean(A ./ B);
Aestimated = factor * B;

However B will not match up with A everywhere.

Are you trying to do Multivariate Curve Resolution but just don't know it? This is where you can get a set of "loadings" for building up an arbitrary curve with a set of predefined "library" curves. So using the proper weights (loadings) you can weight and sum the library curves to get you your desired curve.