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Trilinear interpolation in mathcad prime?

thread552-501560

Trilinear interpolation in mathcad prime?

Trilinear interpolation in mathcad prime?

(OP)
Hi all!

I'm attempting perform linear interpolation with 3 independent variables, like so:



The goal is to extract the rows corresponding to d0..d3 based on the inputs a, b and c.

Here is a simple test data set that I have put together:
Excel sheet here

I have done interpolation with 2 independent variables using the Bicubic2D function, but this get's me lost. My best attempt now is to do a simple linear interpolation ('a' to find 'b'), then use the Bicubic2D function to find the dependent variable.

Any tips or hints or resources to help me along the way?

Cheers

RE: Trilinear interpolation in mathcad prime?

So d0 to d3 are the coefficients of the polynomial for each e. Can I guess that this is a factorial experiment with 2 factors at 2 levels and one at 5 levels.

I do not see how you can generate your values for each e without some underlying data or equation. That is, what are you fitting?

So I think you need to explain what you are trying to do. AT the moment all I've got is wall of numbers with no rationale. Using a cubic function when you say you want linear interpolation sounds a bit sus.

Cheers

Greg Locock


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RE: Trilinear interpolation in mathcad prime?

That kind of interpolation of a tabled "function" in three independent variables was posted a few times in the native Mathcad forum at PTC https://community.ptc.com/t5/Mathcad/bd-p/PTCMathc...
It can be done using linear interpolation as well as cubic spline interpolation and the tabled data has to be provided in a special way.
You may search that forum but the search function often is of not much help and so you may consider posting your question there in a new thread. I am sure someone will be able to come up with the solution functions you need.

RE: Trilinear interpolation in mathcad prime?

I might be wrong, but is this uniquely defined? Your second set of data and the seventh set have same a, b and c values, with different e values - is that correct?

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