indepvar and depvar are of inconsistent sizes with polyfitn

when i use polyfitn with matlab say indepvar and depvar are of inconsistent sizes and i don't now where i am wrong can yo help me?

this is the data:

x1=[2.2 2.2 2.2 2.44 2.49 2.48 2.45 2.2 2.39 2.38];

>> x2=[29.4 30.9 32.9 26.9 28 28.8 30.1 29.4 28.8 30];

>> y=[7.5 7.02 6.94 7.91 7.96 7.91 7.78 7.42 7.86 7.47];

p=polyfitn([x1,x2],y,1)

Error using polyfitn (line 172)

indepvar and depvar are of inconsistent sizes.

Answer 1

[Bjorn Gustavsson]

Yes, you send in an array [x1,x2] of size [1 x 20] and an array y of size [ 1 x 10] into polyfitn. The polyfitn version I have (a matlab-central submission by John d'Errico from 2006) gives me a more sensible result after transposing your inputs:

 p=polyfitn([x1;x2]',y',1)
p = 
      ModelTerms: [3x2 double]
    Coefficients: [1.5589 -0.11979 7.4607]
    ParameterVar: [0.1693 0.0010284 2.9687]
    ParameterStd: [0.41146 0.032068 1.723]
              R2: 0.91523
            RMSE: 0.10284
        VarNames: {}

This was my curse when starting to use matlab - I solved it by the very sofisticated technique:

If it doesn't work transpose, transpose again until all combinations have been tried.

You might do the same but a more intelligent aproach is to check the documentation and input variables.

HTH

[mohamed gryaa]

thanks for helping me