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Interpolation & Extrapolation VIs

LabVIEW 2013 Help

Edition Date: June 2013

Part Number: 371361K-01

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Owning Palette: Mathematics VIs

Requires: Full Development System. This topic might not match its corresponding palette in LabVIEW depending on your operating system, licensed product(s), and target.

Use the Interpolation & Extrapolation VIs to perform 1D and 2D interpolation, piecewise interpolation, polynomial interpolation, and Fourier interpolation.

Palette ObjectDescription
Create Interpolating PolynomialTakes the piecewise polynomial x locations and a 2D array of coefficients and forms the piecewise polynomial cluster for the Evaluate Interpolating Polynomial VI to use.
Create Mesh Grid (2D)Takes two x domain and y domain arrays and forms X and Y 2D arrays, which are typically used to evaluate and plot functions of two variables. You must manually select the polymorphic instance to use.
Evaluate Interpolating PolynomialTakes the piecewise polynomial cluster and computes the interpolated values yi at each xi location.
Hermite Interpolation 1DPerforms one-dimensional interpolation using the cubic Hermite interpolation method based on the lookup table defined by X and Y.
Interpolate 1DPerforms one-dimensional interpolation using a selected method based on the lookup table defined by X and Y.
Interpolate 1D FourierPerforms interpolation by transforming the array X into the frequency domain, zero-padding and scaling appropriately for the interpolation factor you want and to maintain correct symmetry in the frequency domain, and then transforming back into the time domain to form the output interpolated array Y out.
Interpolate 2DPerforms two-dimensional interpolation using a selected interpolation method based on the lookup table defined by X, Y, and Z, where Z is a 2D array. You must manually select the polymorphic instance to use.
Interpolate 2D ScatteredPerforms two-dimensional interpolation on scattered points.
Polynomial InterpolationInterpolates or extrapolates the function f at x given a set of n points (x[i]y[i]), where f(x[i]) = y[i], f is any function, and given a number x value.
Rational InterpolationInterpolates or extrapolates f at x value using a rational function. The rational function passes through all the points formed by Y and X.
Search Ordered TableWorks on the assumption that ordered x array is in monotonically increasing or decreasing order and can therefore efficiently search for the relative index of the location of x value within the x array. The VI starts the search at the starting index and begins by using a fast hunting phase to roughly bracket the location and then narrows to the final bracket using a bisection search. The VI computes the fractional index location by using linear interpolation.
Spline InterpolantReturns an array Interpolant of length n, which contains the second derivatives of the spline interpolating function g(x) at the tabulated points x[i], where i = 0, 1, …, n–1.
Spline InterpolationReturns a spline interpolated value at x value given the tabulated values (x[i], y[i]) and the second derivatives Interpolant that the VI obtains from the Spline Interpolant VI.
Spline Interpolation 1DPerforms one-dimensional interpolation using the spline interpolation method based on the lookup table defined by X and Y.

 

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