LSFit 3 variables  Chose a power 1 to 5.
  Provide data in form below to get the least square polynomial
  fit of your data. Or, click on Browse and get your data from a file.

  x and y denote independent variables, u denotes output
  
  u = c0 + c1*x + c2*y + c3*z                      for first power,  at least 4 data
  u = c0 + c1*x + c2*y + c3*z + c4*x*x + c5*x*y +
      c6*x*z + c7*y*y + c8*y*z + c9*z*z            for second power, at least 10 data
  u = c0 + c1*x + c2*y + c3*z + c4*x*x + c5*x*y +
      c6*x*z + c7*y*y + c8*y*z + c9*z*z +
      c10*x*x*x + c11*x*x*y + c12*x*x*z + c13*x*y*y +
      c14*x*y*z + c15*x*z*z + c16*y*y*y + c17*y*y*z +
      c18*y*z*z + c19*z*z*z                        for third power,  at least 20 data
      c0 to c24                                    for fourth power, at least 25 data
      c0 to c56                                    for fifth power,  at least 57 data

power

enter your data  x  y  z  u  each floating point number followed by a space
fit 
 

data