title: What's the meaning of parameter "knots" in function "spmak" (in matlab)
body: <p>I have a data set which saved in matrix "data", it is of two-dimensional.  I want to fitting a curve with the function "spmak" in matlab using this data set. How to do ? 
      SPMAK(KNOTS,COEFS):the function prototype in matlab. what's the meaning of "knots" and "coefs"? How can I get the two parameter from the data matrix "data"?</p>