Global error data set & mathematica cubic spline

[pat666]

Hey, I have a data set (electronic device output) which we need to find the best fit via approximation and interpolation. I've done a cubic least squares, then found the local error for all the given points (actual - approximate). We need to also find the global errors for the methods we choose but I don't know what the global error is or how to find it??

Also I am doing a cubic spline interpolation and need to do the same thing regarding errors but first I need to make mathematica 8 do the spline. Any one know the code for this?


Thanks

 

[lippyka]

!The global error is the average of the local errors. To find the global error, you need to sum up all the local errors and divide by the number of data points. For the cubic spline interpolation, you can use the Interpolation function in Mathematica 8. Here is an example for a dataset consisting of x values from 0 to 10 and y values from 0 to 10: list1 = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; list2 = {0, 1, 4, 9, 16, 25, 36, 49, 64, 81, 100}; f = Interpolation[Transpose[{list1, list2}], InterpolationOrder -> 3]; This creates an interpolating function f that you can use to evaluate any points inside the range.