How can I find coefficients for a sinusoidal function?

The user inputs data in xy pairs separated into columns. The code is supposed to give a sinusoidal regression fit using only simple matlab functions, no toolkit or addons of any kind. I know the format is supposed to be Asin(B*X+C)+D, bud don't know what function can find these coefficients. I have very minimal experience with coding so some explanation would also be appreciated.

Answer 1

[Star Strider]

An oldie but a goodie: Curve fitting to a sinusoidal function (link)