Queries on [x,y] in the fit function

I have a matix where the rows are the x values, columns are the y values and the matrix elements are the z values. I want to try to use the "fit" function in matlab to plot them. (My matrix has 3500 rows and 250 columns)

fitobject = fit([x,y],z,fitType) creates a surface fit to the data in vectors x, y, and z.

I have tried reading the documentation of this function. However, I still don't understand the input parameters [x,y],z should look like.

For example: For x it says "Data to fit, specified as a matrix with either one (curve fitting) or two (surface fitting) columns. You can specify variables in a MATLAB table using tablename.varname. Cannot contain Inf or NaN. Only the real parts of complex data are used in the fit." Why should my x have 2 colums? And what should I put for y inin such a case.

If someone could elaborate on how my the input parameters in more detail, I would be really grateful.

Answer 1

[Vinay Konanki]

Hii Akaash,

Consider the statement below,

fitobject = fit(X,Z,fitType); 

You can consider X (or x mentioned in the documentation) as the first argument to the fit function.

There are two acceptable cases.

1. The first one being X = x where x is a vector (matrix with a single column).
2. The second one is X = [x,y] where x and y are vectors which makes X (the first argument to the fit function), a matrix with two columns.

The first case leads to a curve fit where as the later case leads to a surface fit.