Does spline-interpolation work? (what's it supposed to do?)

[bluesbros]

Hello!

      I was told (by a co-worker) that Spline_Interpolation[Xi] should exactly match a "tabulated" Y (input) if Xi was one of the "tabulated" X input values.  I don't know if this is correct - if it is, then the function isn't working as expected.  Any insight is appreciated.

Thanks in advance!

[MattBradley · Accepted solution]

Mathematically, the way that spline interpolation work is that it fits the curve so that the fitted data passes through every experimental data point.  This is unlike linear or polynomial curve fits, which minimize the overall error.

One thing that you *might* be doing wrong is reversing the x and y data.  Can't look at your code right now.

[tbd]

Hmm...  I think the X and Y are right, but wiki says X is supposed to be increasing and in the VI above, X is decreasing.  After reversing X-array, exact Y values show-up as expected - excellent!  I'll cautiously-consider this is the cure.

You got me to focus on getting inputs correct,

thank you Matt!

Doh! At work I'm "bluesbros" (who's email has a service-agreement )  

Message Edited by tbd on 04-21-2009 12:06 AM

[bluesbros]

Thanks (again) Matt.