I have a sequence of $n$ points $(x\_i,y\_i)$, for $i=1,\dots,n$. I would like to find the function, of the form $y=V\sin(x+\phi)$, which best fits the points. Which numerical method could I use? I have a slow system, with little memory, so I am searching for a fast and efficent method, even if not very accurate.

I have tried with gradient descent, but it is slow.