Fitting data that goes beyond a single line in Trial Version

Questions
1

Dear All,
Can someone please help me in fitting the following the data in trial version of Mathematica 10?
{

 2.6,2.6,120,-170.7255},
{ 2.6,2.6,110,-170.7338},
{ 2.6,2.6,100,-170.7432},
{ 2.6,2.6,90,-170.7547},
{ 2.6,2.6,85,-170.7612},
{ 2.6,2.6,70,-170.7910},
{ 2.6,2.6,60,-170.7931},
{ 2.6,2.6,50,-170.7682},
{ 2.6,2.6,40,-170.4559},
{ 2.6,2.6,30,-168.3291},
{ 2.4,2.4,120,-170.7255},
{ 2.4,2.4,110,-170.7338},
{ 2.4,2.4,100,-170.7432},
{ 2.4,2.4,90,-170.7547},
{ 2.4,2.4,85,-170.7612},
{ 2.4,2.4,70,-170.7910},
{ 2.4,2.4,60,-170.7931},
{ 2.4,2.4,50,-170.7682},
{ 2.4,2.4,40,-170.4559},
{ 2.4,2.4,30,-168.3291}

I already have the form of the fitting functions. Fitting data which can be contained in a single line of notebook does not come out with any error. Putting \ at the end of line also did not give any success. Where am I going wrong? Any comment(s) would be of great help. Thanks in advance.

2

Dear Himadri,

Welcome to the Wolfram Community. Could you please include all the code, the fitting model, and the things you have tried. With the current information you gave us, we really can’t help you.

Also, please change the ‘groups’ you posted this question in. These are just some random groups you selected…

3

Thanks for reply. I tried to run the following:

Fit[ {  { 2.6,2.6,120,-170.7255}, { 2.6,2.6,110,-170.7338}, { 2.6,2.6,100,-170.7432}, { 2.6,2.6,90,-170.7547}, { 2.6,2.6,85,-170.7612}, { 2.6,2.6,70,-170.7910}, { 2.6,2.6,60,-170.7931}, { 2.6,2.6,50,-170.7682}, { 2.6,2.6,40,-170.4559}, { 2.6,2.6,30,-168.3291}, { 2.4,2.4,120,-170.7255}, { 2.4,2.4,110,-170.7338}, { 2.4,2.4,100,-170.7432}, { 2.4,2.4,90,-170.7547}, { 2.4,2.4,85,-170.7612}, { 2.4,2.4,70,-170.7910}, { 2.4,2.4,60,-170.7931}, { 2.4,2.4,50,-170.7682}, { 2.4,2.4,40,-170.4559}, { 2.4,2.4,30,-168.3291} }, {1,x,x^2,y,y^2,z,z^2,xy,yz,zx},{x,y,z} ]

This is what is desired. As I mentioned, data which can be contained in a single line of notebook does not come out with any error, I get the desired function. Putting \ at the end of line of notebook also did not give any success.

4

Remember that xy is a single variable. You need to put a space in between the x and the y in order to indicate that it is a multiplication of two variables. Same for yz and zx.

5

Thanks. But the same worked perfectly when the data set was limited to four rows, which apparently is limited to a single line in the notebook. However, I will put the space in future to denote x*y is a single variable in Mathematica. The problem still persists for my entire set of data. Any comments will be of much help.

6

Please attach your notebook to a post here. Otherwise we can’t figure out what you are trying to do.

7

The answer was in the 3D+2D graph.

8

In1:= data = {{2.6, 2.6, 120, -170.7255}, {2.6, 2.6,
110, -170.7338}, {2.6, 2.6, 100, -170.7432}, {2.6, 2.6,
90, -170.7547}, {2.6, 2.6, 85, -170.7612}, {2.6, 2.6,
70, -170.7910}, {2.6, 2.6, 60, -170.7931}, {2.6, 2.6,
50, -170.7682}, {2.6, 2.6, 40, -170.4559}, {2.6, 2.6,
30, -168.3291}, {2.4, 2.4, 120, -170.7255}, {2.4, 2.4,
110, -170.7338}, {2.4, 2.4, 100, -170.7432}, {2.4, 2.4,
90, -170.7547}, {2.4, 2.4, 85, -170.7612}, {2.4, 2.4,
70, -170.7910}, {2.4, 2.4, 60, -170.7931}, {2.4, 2.4,
50, -170.7682}, {2.4, 2.4, 40, -170.4559}, {2.4, 2.4,
30, -168.3291}};

In[2]:= fit[x_, y_, z_] = 
 Fit[data, {1, x, x^2, y, y^2, z, z^2, x y, y z, z x}, {x, y, z}]

Out[2]= -116.822 - 19.94 x + 2.65866 x^2 - 19.94 y + 2.65866 x y + 
 2.65866 y^2 - 0.102906 z - 1.50851*10^-15 x z - 1.50851*10^-15 y z + 
 0.000593404 z^2

In[3]:= Plot3D[fit[x, y, 50], {x, 2.4, 2.6}, {y, 2.4, 2.6}, 
 PlotLabel -> "Z = " <> ToString[50], AxesLabel -> {"X", "    Y", ""}]

fitxyz1.png
fitxyz1.png360×276 41.2 KB

In[4]:= Table[f[x, y, 50], {y, 2.4, 2.6, .1}] // Evaluate

Out[4]= {f[x, 2.4, 50], f[x, 2.5, 50], f[x, 2.6, 50]}

In[5]:= Plot[
 Table[fit[x, y, 50], {y, 2.4, 2.6, .1}] // Evaluate, {x, 2.4, 2.6}, 
 PlotLegends -> LineLegend[Range[2.4, 2.6, .1], LegendLabel -> "Y"], 
 PlotLabel -> "Z = 50", AxesLabel -> {"X", "Fit"}, LabelStyle -> 16]

fitxyz2.png
fitxyz2.png429×244 5.12 KB

9

Thanks a Million !!!