I want triangular wave fitting.

[yeers]

hello .
I end up needing a triangle wave fitting.
This is because we need to distort the triangle wave. 

I don't know what the problem is in your current VI.

I am trying to fit a signal like the one in the picture above with a triangular wave.
I'm having trouble putting together an example code.

regards

[altenbach]

Your picture does not show a triangular wave.

Nobody in his right mind would use the formula version of Levenberg-Marquardt. (Besides, your model description has several issues). Start with creating a proper model VI, and make sure it calculates something resembling your data given the parameter estimates.

For more examples, have a look at my group here.

Can you write out the formula you like to fit?

Your current input data looks as follows. Where exactly do you see a "triangle wave"?

[yeers]

Thanks to reply

fist I want to distortion wave form to triangular 

below image A to B

A

B

So, Ignore the arrays in the sample code.
Can I finally fit these A waveforms to B or

do I need to use a different method for distortion?

I'm checking your sample code .

Regards

[altenbach]

A and B look very different. Do you have some real data?

What is the model equation? What are typical model parameters?

[yeers]

1. Original wave form data in VI file

2. I tried expressing an expression using a formula node.

 z = x / T; // Normalize x by period
frac_part = z - floor(z); // Fractional part of z
y = A * (2 * abs(frac_part - 0.5)) + C; // Triangle wave formula

So parameters is 

A : amplitude

T : peroid

x: time

C: offset

If there is a different way to distort the triangular wave, please let me know.