MATLAB Curve fitting with custom equation (max/min)

Hi,

I would like to write my model equation: Asinx+k and I know that k=[max(data)-min(data)] / 2 for my dataset

How can i write k in curve fitting with custom equation?

Best Regards,

Answer 1

[Matt J]

It is better not to use a custom equation when one is not needed. Just fit the 'sin1' model to y-k.

fitobject = fit(x,y-k,'sin1')

Answer 2

[Walter Roberson]

You can bind it in using an anonymous function; http://www.mathworks.com/help/matlab/math/parameterizing-functions.html

However, I wonder if it is worth doing?

y = A*sin(x) + k   %with known k
y - k = A * sin(x)
A = (y - k) ./ sin(x)

and for fitting purposes, the best A would be mean() of the right hand side.