How to give more than one vector as input to polyfit() function?

I have a 27x3 matrix of three input variables and one corresponding vector(27x1) as output. I want a polynomial regression equation relating the inputs and the output. The polyfit function gives the following error when given the command: polyfit(input, output, 3)

Error using polyfit (line 48) X and Y vectors must be the same size.

I am new to matlab and so please bear with the noob question. If I am using the wrong function, please let me know the correct procedure for the same.

Thanks in advance,

[Jan]

And what is the relation between the 3 input vectors and the wanted output? Did you read the docs of polyfit? The first input is the vector of X-values and the second the vector of Y-values. So I cannot imagine what you mean by "input" and "output".

[Akash]

Hello Mr Jan Simon,

Actually I have three values for X, i.e. X1, X2, X3, and the polyfit function takes only one vector as input. I want a relation between X1, X2, X3 and Y, so I combined X1, X2, and X3 into a matrix (input) with the variables as the columns and used this matrix as a single input value to the function polyfit. At this point the previously mentioned error appears. Thanks for answering

Answer 1

[Star Strider]

The polyfitn function from the File Exchange may do what you want.

[Akash]

Thanks for the suggestion. The polyfitn function worked for me.

[Star Strider]

My pleasure!