Community Tip - Visit the PTCooler (the community lounge) to get to know your fellow community members and check out some of Dale's Friday Humor posts! X
Hello,
I want to fit with minerr a sinus function. The sampled xy-dataset consists of e.g 20 periods of a sinus signal. I want to know the period (time of oscillation) of each of the 20 periods. In a loop I want to fit with minerr the data. How can I do it? I attached the data-file and the mathcad 15 document with with the programming I've done so far (just look at the red marked boxes).
thanks.
ur
what do you expect to get with (F(as,X) - Y)^2 ? If you want these to matrices to be (as) equal (as possible), you would have to write F(as,Y)=Y instead.
Q(Y)= gives you a 4x1 vector with values slightly different from the start value as. Q(D) gives you still an error because the way you have written it Q is a function with a 500x20 matrix as the argument, D is a 500x1 vector - the dimensions simply do not match.
Y is and F returns a 500x20 matrix, the difference is a 500x20 matrix, too.
You can not square a non-square matrix and thats why Mathcad delivers the error message "This matrix must be square" when you try to use Q (a function you assigned minerr to) the first time.
Since you have such a nice sinusoidal signal, why not use an FFT to derive the fit:
Turn the solve block into a function, and call the function in a loop.
If you are minimizing a vector of residuals make sure mineer is using the LM algorithm.