checking script's output

Hi all,
i've uesd those two code in a script to fit a polynomial on my data.the evauation output(command: polyval2(P,x,y))tells us,it's a good fit but when i made the equation with coefficients which produced by P = polyfitweighted2(x,y,z,9,w)i couldn't reach to that evaluated point( tested at specific point)which is produced by the coomand polyval2(P,x,y).i would like to ask somebody plz help me to find how could i get to a evaluated point through equation at a point???

   link for two functions :
  http://www.mathworks.com/matlabcentral/fileexchange/13719-2d-weighted-polynomial-fitting-and-evaluation

my script:

BoverH=1:8;
phi=0:10:30;

mydata = [ 1  1.02   1.11  1.21  1.3   1.4  1.59  1.78; ...   
        1    1.11  1.35  1.62  1.95  2.33   3.34  4.77; ...
        1.01  1.39  2.12  3.29  5.17  8.29  22    61; ...
        1.13   2.5   6.36  17.5   50   150  1400  14800];

h=log(mydata);   

y=phi;
x=BoverH;
z=h;
w=ones(size(z));
P = polyfitweighted2(x,y,z,9,w);

[c, hh]=contour(x,y,z); clabel(c,hh), colorbar
title('data')
figure
[c, hh]=contour(x,y,polyval2(P,x,y)); clabel(c,hh), colorbar
title('equal weight')

[milad babaei]

According to the script and the function P = polyfitweighted2(x,y,z,9,w) and command polyval2(P,x,y),we able to make equation with coeff.which are made by function P.and evaluted the equation at a specific point like(X1,Y1).but my problem is :i couldn't get that equation to check and evaluate at the point which this command polyval2(P,x,y) gives me on output.i would like to ask you help me on making z equation .for example i reached to the equation after running the script and producing coefficients :

z=log(h): -0.0026-.0009(x^3)+0.0033(x^5)-0.0017(x^6)+0.003(x^7)-0.0004(x^6*y)+0.0004(x^4*y^3)-0.0002(x^3*y^4)+0.0001(x^2*y^5)

x=(B/H),y=phi..........at this (x=4 and y=0)point for evaluating fitted equation and checking the result of polyval2(P,x,y).it gives me z=log(h)=1.271....which h=e^1.271=3.56 but according to polyval2(P,x,y) output for this point gives us e^0.1936 =1.21??????

so my question is :is that equation which i have made with those coefficients correct???and why i couldnt get those evaluated number through the equation?also whats the W on a

> coefficients definition(wZ) on a script definition??