Where do I search for mathematical modeling of data exhibiting trends arising from a general function of sinusoidal equations? I am not referring to the Fourier analysis. In the Fourier analysis, we consider the addition of sinusoidal functions. This data is where the data is a function of multiplicative sinusoidal functions such as
f(t) = A1*sin(W1*t) * A2*sin(W2*t)* A3Sin(W3*t)….
Or
f(t) = A(t)*sin(W(t)*t) ,
where A(t) and W(t) can take any other functional form.
Is there any literature that describes a method for identifying such terms?