I am trying to fit f(x) = sin(x)*sin(x) function to my data like this:

```
Func<double, double> fit = Fit.LinearCombinationFunc(
xData,
yData,
x => 1.0,
x => Math.Pow(Math.Sin(x + 1.0), 2));
```

But the phase of “fit” is a bit off:

My data could have random phase shift every time a acquire it and that is the main problem with this fitting.

What I am doing wrong?