I would like to define the function with Fourier series when I just have discrette data. (I don't have a specific function).
I can draw the graph using the data, but I don't have a idea how can I get this function. The plot is a periodic.
I want to obtain a function that will work like a Fourier series expansion. How can I define such a function?
Graph

Horizontal-axis is Time. Vertical-axis is Space.