Questions tagged [interpolation]

Questions on the interpolation functions in Mathematica (InterpolatingFunction[], Interpolation[], ListInterpolation[], FunctionInterpolation[], InterpolatingPolynomial[], etc.)

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3answers
138 views

Removing some data and replacing them with new ones

I have a data list where the elements have the form (time, velocity ). I need to remove some malformed elements in places where the data does not change smoothly and then replace those points by ...
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1answer
700 views

Interpolation of a table with 4 parameters

I have a huge data file which I need to do some analysis on it. The file is built in this way that for each 4 variables, there is a value of the function: ...
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1answer
276 views

Partitioning a numerical integral: need to integrate spectra

I am trying to integrate a spectrum I obtained from a fourier transform infrared spectroscopy experiment, in order to determine the global warming potential of green house gases. In order to do this, ...
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1answer
617 views

Interpolation problem on the list

I have a List of Latitude, Longitude and Measurement. a = {{{93, 104}, 290}, {{94, 103}, 292}, {{95, 105}, 291}, {{97, 109}, 294}, {{97, 102}, 295}}; And, I ...
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1answer
919 views

Optimizing the fitting of Ordinary Differential Equation(NDsolve) involving interpolation functions

I am a newbie to this forum. I am trying to use NDsolve to solve some ODEs involving the interpolation function. Then, I will compare the fitted curve and data to determine the ODE coefficients. ...
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0answers
98 views

FEM 1D 3D region coupling - integration too slow for coupling with energy conservation

EDIT: I reposted this question, removing everything that is not necessary for my coupling approach. Find the new post here. I am working on a 3D simulation of the heat equation which is coupled to a ...
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0answers
43 views

Integrating and seeing an interpolating function

I have the following piece of a Mathematica notebook: As I understand, the interpolating function M1hatInterp is piecewise polynomial and hence can be integrated ...
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0answers
38 views

Why ListInterpolation does not allow InterpolationOrder greater than 2 in the "y" direction?

The order is always reduced to 2 in the "y" direction; I would want a better approximation to my data. Independent of the method (spline or hermite), I can choose any order for the "x&...
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0answers
50 views

Interpolation for different Parameters

I am rather new to Mathematica and I tried to find a solution for my Problem on my own, also looking through this site and the suggested Similar Questions, but I at least could not make out that my ...
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0answers
97 views

linear interpolation error [closed]

I have two set of data for pressure and energy density and I used a linear interpolation to apply the data as a function in terms of each other. ...
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0answers
45 views

Finding specific x value when y axis is zero [closed]

If I have the following data: https://pastebin.com/4F7R0nW0 Which plotted using ListLinePlot[data, PlotRange -> {{80, 110}, {-0.020, 0.05}}] gives: Question: ...
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2answers
93 views

Integrate over one variable of a 2D interpolating function returned from NDEigensystem

I'm trying to implement the answer for "Integrate only one variable of a 2D interpolating function" (https://mathematica.stackexchange.com/a/161962/73672) but for interpolating functions ...
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0answers
28 views

Variable order in InterpolatingFunction

I'm attempting to deal with a interpolating a function $f[x,t]$ on an unevenly spaced grid of $n$ points. My x-variable is continuous, so there's no difficulty in fitting a cubic spline to it with ...
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0answers
74 views

Numerical Definite Integral of Numerical Laplace Transform

I'm having problem taking the numerical definite integral of a numerical Laplace transform that depends on two variables due to NIntegrate:inumr errors: ...
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0answers
70 views

Numerical integration of a function with several variables

I need to calculate the next integral $$ F_l(R)=\int_0^{\infty} {dk k^2j_l(k R)*2*\exp[-0.36k^2](k)\rho_l(k)(18/k^2)P_l(\cos{\beta})}$$ where ρl(k) is given by $$ \rho_l(k)=\int_{0}^{\infty}{dr r^2 ...
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0answers
54 views

Axial Symmetric 2D Cylindrical Field to Cartesian 3D Field

Previously, I've used 2-dimensioned [radius, zeta] output from NDSolve ({InterpolatingFunction, InterpolatingFunction}] and used the FieldTransform to convert the axial-symmetric cylindrical slice to ...
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0answers
52 views

Why doesn't Sort work in this case ? (Only numerical values)

Context I want to interpolate a complicated symmetric function f of 2 variables x and y defined by some numerical integral involving Bessel functions. Since computing the integral itself is a bit ...
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0answers
81 views

NIntegrate 3D Interpolation function in a region extracted from ListContourPlot3D

I have a list of 3D volumetric data points, e.g. for every position in 3D space there is a value. What I want to do is to firstly use "Interpolation" to get a function form of the data f[x,y,z] and do ...
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0answers
58 views

Interpolating a density plot

I am solving a complicated series of equations (involving FindRoot and PolyLog), and finally I get this plot Code here: ...
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1answer
55 views

How to convert Piecewise function to Interpolation function?

In the following piece of code I am trying to convert a Piecewise function to a simple interpolation function f[t_] ...
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1answer
82 views

Find Unknown coefficient using Contour plot

I have I really complicated equation, but for simplicity lets assume my function is F(x,y,z)= ax+by+c*z, where a, b and c are some unknown constants. From experiments we know that at: x=3, y=2, z=1 ...
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0answers
183 views

Get R^2 value between interpolating functions and a list of points

I am looking to compare the degree of accuracy of a theoretical model by comparing my theoretical curve to my experimental data points. My theoretical curve is an interpolating function generated ...
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0answers
64 views

Interpolation of multidimensional data: some domains are lost

I am trying to make a reasonable interpolation of a dataset having the form dataset = {{x1,x2,x3,f[x1,x2,x3]},...}. I to the interpolation in the following way: <...
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1answer
88 views

Smooth plot of coarsely spaced table values [closed]

In a simpler first case I plotted reasonably spaced (stability) contours by selecting a sequence of k values, ...
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0answers
40 views

Plotting 3D points with function as contour

so I have a grid of points in 2D $(x_i, y_i)$, and a function $f(x_i,y_i)$. I plotted them together like this: -- Now I would like to do the same with a grid of 3D points $(x_i, y_i,z_i)$ and a ...
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0answers
48 views

how to use interpolating functions to smoothly paint a polygon? [duplicate]

consider 4 different colors on the nodes (with different parameter values) how to interpolate when the color values are given on the nodes using the constructed interpolation functions to paint the ...
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2answers
149 views

How to interpolate my results at discrete steps? [closed]

I have the results ...
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0answers
68 views

Interpolation with symbolic variable to speed up numerical integral [closed]

I have the following integral: $$E(r) = \int^{\infty}_0 e^{-x^2} e^{i\pi(ax^2 - \frac{x}{\Delta})}J_0(r\,x)x \,\mathrm{d}x,$$ where $J_0$ is the zeroth Bessel function of the first kind. Two ...
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0answers
229 views

Unable to Solve Area Using Paramteric Equations derived from The Numeric Soution of a Differential Equation

I'm creating a test that measures the distribution of closed shape $\mathcal{C}$. This requires taking the average ray length (from $(u,v)$ in $\mathcal{C}$ to the boundary) using ray length per ...
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1answer
399 views

InterpolatingFunction::dmval error in the Piecewise function with an interpolation funcion included

I have a set of data, first I deal the data with an Interpolation function. excitef1 = Interpolation[ps1] Then I use a Piecewise function to expand the range of ...
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0answers
76 views

Speeding up a minimisation involving Numeric integral and Interpolating function

I am doing a minimisation procedure to obtain best fit parameters a,b,NN for a model involving a numeric integral and an interpolation function. The code as written ...
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0answers
146 views

How to quickly evaluate the same interpolating function many times?

i am trying to use NDSolve on a set of coupled ODEs (roughly 200 equations). In each equation an interpolating function has to be evaluated many times at the same point respectively. So for example ...
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0answers
68 views

How do I find the best fit line which passes through a series of data? [closed]

I have a list of data and want to create a function which passes through them. I'm new to Mathematica and don't know how to do this work. Could anyone explain this topic with fitting the below data?...
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0answers
43 views

Interpolation with order All function object not given as output

I use mathematica10.4 and want to interpolate uneven data in 3 independent variable, (say r1, r2, r3). Because it is an unequally spaced data, I prefer interpolation order->All. But when I run the ...
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0answers
136 views

Understanding the structure of an InterpolatingFunction [duplicate]

FunctionInterpolation[x^2, {x, 0, 9}] // InputForm returns: ...
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0answers
97 views

Using FindMaximum on one component of a vector-valued function

I've got a physics simulation that uses NDSolve and returns a vector-valued InterpolationFunction, by which I mean that the <...
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0answers
446 views

How can I suppress InterpolatingFunction::dmval message? [closed]

I'm getting this error again and again even though I have interpolated my function from -3 to 3. InterpolatingFunction::dmval: Input value {-2.99957,-2.99957} lies outside the range of data in the ...
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0answers
72 views

3DPlot, Logarithmic x and y axes, Interpolating function [closed]

I've used NDSolve to get an InterpolatingFunction that solves a certain difeq. I want to see the behavior of this function on a couple different scales, so I want to use some sort of Log Plot. For a ...
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0answers
166 views

DeleteDuplicates [closed]

After having applied "DeleteDuplicates" to a list of data (15000 rows per 3 columns), when I try to interpolate that list of data it gives me back again: "There are duplicated abscissa points in.." ...
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0answers
556 views

Smoothing ListContourPlot contours for unstructured grids. Part 2

My question is motivated by the following discussion. Smoothing ListContourPlot contours I need to generate high-quality contour plots for some property generated on a non-rectangular grid. This is ...
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0answers
581 views

Obtaining values from interpolating functions

A similar question has been asked in the post HERE but the current question is more complicated: I have the following differential system ...
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0answers
426 views

How to use interpolating functions in NSolve with a piecewise function?

I have a system of two non-linear differential equations that are piecewise, the solutions of which I would like to use to obtain the values of a third variable that is also piecewise. I have trouble ...
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0answers
542 views

Getting FindRoot::nlnum when trying to find root of an Interpolating function [closed]

I want to solve a system of differential equations and find a point where the solutions cross. So four steps: 1. Solve the system of differential equations: ...
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0answers
142 views

Absurd solution by LinearSolve

I am trying to find curve that passes through all the data points.To do this i am doing interpolation using LinearSolve. No. of equations vary from 1000 to 3000. LinearSolve gives me values of ...
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0answers
290 views

Determining the order of continuity (smoothness) of a function

Is there any method to determine the order of continuity of a function (just like an interpolant) over a given domain, or at least determine the continuity on a given order? For example, according to ...
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0answers
83 views

Continuous integration of a tensor function using discrete density values

Hei, I am wondering is it possible to implement continuous integration using Integrate() of a fourth order tensor with discrete density values. ...
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0answers
112 views

Improving RationalInterpolation Result

The following code produces a {4,4} rational interpolation approximation accurate to 10^-6 or better over the range ...
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0answers
93 views

Show actual Interpolation function [duplicate]

Is there a command to show the actual function when using the Interpolation command? For example, f = Interpolation[{1, 2, 3, 5, 8, 5}] returns ...
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0answers
89 views

Conjugate of InterpolatingFunction?

From NDSolve, I got this: {{a1 -> InterpolatingFunction[{{0., 40.}}, "<>"]}} What would be a sensible approach to ...
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0answers
227 views

How to write my own interpolation method [duplicate]

I was comparing results of spline interpolation in Mathematica and C++/gsl-library Results of interpolation are different if I use ...

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