fitting spline on data and getting equation

      i have a table with 3 variables(B/H)= 1,2,3,4,5,6,7,8 and fi= 0,10,20,30 and h which is depend on (B/H) and fi that contains 32 values. for example for fi=0 and (B/H)=1 >>h=1 fi=0 and (B/H)=2 >>h=1.02 ...... fi=30 and (B/H)=8 >>h=14800

    h:[ 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]

>>>>is there any way in MATLAB to fit spline on data and get equation for h in terms of (B/H) and fi??and how could we make sure that spline is a good fit for our data???

[Andrei Bobrov]

Hi milad!

it does not suit?

<http://www.mathworks.com/matlabcentral/answers/10582-deriving-surface-equation-form-data-on-a-table>

[milad babaei]

Hi dear,

would you please answer my 2 comment below that previous code that u mentiond above?i have question about other h values on table and then about how u consider h values???on the other hand because of large range of h values from 1 to 14800 i coouldnt find any 2dweighted polynomial to fit well.so i am looking for a spline to fit well on h vales.would you please help me more to solve this problem anyway??

Answer 1

[Bjorn Gustavsson]

If you have the spline toolbox you should take a look at spas2, spaps and csasp.

HTH,

[milad babaei]

would u plz help me on using csasp ?how should i introduce my values??i am new to MATLAB world.

[Bjorn Gustavsson]

At the command line type: help csasp

There should be some example in there, that you hopefully can adjust. When you get problems with that, comeback with specific questions, and we'll help you further.

[milad babaei]

tnx for your help, i plotted my data with mesh command and then try to 2d interpolate with inter2(linear method gives me better answer than spline somehow) and get pretty answer on interpolation.now i would like to know is there any way to find that equation which fitted my data and and also evaluate the interpolated data???

[deb.P]

i have the same question, that i have fitted a curve to my 3 variable data set. Now i want to know what is the equation of the fitted curve.