Questions on the interpolation functions in Mathematica (Interpolation[], ListInterpolation[], FunctionInterpolation[], InterpolatingPolynomial[], etc.)
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Interpolation and points of non-differentiability
I have some data, which if expressed by some elementary functions, would contain a non-differentiable point. I would like to be able to use something like interpolate to convert the data into a ...
14
votes
2answers
495 views
Fast Spherical Linear Interpolation of list of quaternions
An accurate way to interpolate between two quaternions is to use Spherical Linear Interpolation (Slerp) because it preserves the unit length, whereas straightforward linear interpolation does not, as ...
0
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2answers
107 views
Correct use of ListInterpolation
I have a small problem with ListInterpolation. I want to use ListInterpolation to postprocess result of a numerical simulation. ...
5
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1answer
173 views
0
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1answer
64 views
Notation for numerical solutions to differential equations
Can somebody explain this notation to me? Using Mathematica's first example in the NDSolve documentation:
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3
votes
2answers
113 views
Convert BSplineFunction into two Interpolating Functions
Is there a way to decompose a BSplineFunction output into two functions x[t], y[t] ...
7
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0answers
144 views
Creating and using an explicit piecewise function in a convenient way
I have a set of data points that define a function in the form
curvePts = {data1,data2,...}
where
...
0
votes
1answer
51 views
How to work with Interpolated Functions? [closed]
I am just a beginner and struggeling with experimental data and further processing in Mathematica:
I first constructed a table from two columns (t20 and J20) in Excel:
...
6
votes
1answer
116 views
Smoothing/Averaging 2D Vector Fields
I have a list of 2D vectors defined by {{x,y},{u,v}} and would like to smooth or average the vectors. For example here are 2 vector fields, the second has noise ...
2
votes
1answer
106 views
Interpolation on large 2D list results in erratic function
Previously, I've had problems with Mathematica interpolating and plotting 3D lists, but I finally managed to do so by rescaling the x and y-axes with the help of the methods proposed here. Now my ...
5
votes
3answers
178 views
Interpolation with boundary conditions
I'm working on a sales projection, trying to create some flexibility in handle the forecast using locators.
The toy code is something like this:
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18
votes
1answer
2k views
How does Interpolation really work?
I'm looking for some explanation or advice, not help in solving something. Recently I finished my program and my supervisor said "Ok, now it's time for your first paper: write a scientific text about ...
7
votes
2answers
325 views
Function Interpolation with Automatic / Algorithmic Values Mesh
I have an underlying function f(x,y,z) that is computationally intensive, but is smooth and continuous. I'm needing to find the function values along a line in xyz. Currently, I'm calculating f at ...
0
votes
1answer
133 views
How to add derivatives to Hermite Interpolation?
I try to use
InterpolatingPolynomial[{f[1]=2,f'[1]=3,f[2]=6, f'[2]=7, f''[2]=8}, Method->"Hermite"]
in WolframAlpha, but it's wrong.
4
votes
0answers
141 views
Cubic polynomial interpolation with velocities listed rather than some points
I am trying to use the function BSplineFunction[] to create a natural cubic spline. Normally what is done is that you specify "SplineDegree -> 3" and include a list of points and it will carry out ...
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vote
2answers
114 views
Using FindRoot with an interpolating function
This question bears resemblance to a few other questions on mathematica.SE about finding points of intersection of crossing curves. I know that the guidebook of numerics has an entry about the whole ...
-4
votes
1answer
109 views
Problem with interpolation
I have a problem with the function interpolation. when I use it my points are all very shifted. Do you have an idea of the solution?
...
14
votes
3answers
370 views
Monotone, periodic 1d-interpolation with continuous 1st order derivative
Lately, we had this thread about interpolation where J. M. linked two interpolation methods. The background for my question is that I estimated a parameter in polar coordinates with dependence on the ...
12
votes
4answers
351 views
How to reduce the InterpolatingFunction building overhead?
I want a linear interpolation from the following example list:
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11
votes
3answers
754 views
Data interpolation and ListContourPlot
I am fairly new to Mathematica and I have two quick questions on using it for a Hydrology and Hydrogeology class. One is about data interpolation and interpolating without any data defined in an area. ...
27
votes
3answers
385 views
No warning when extrapolating with Plot
One of the most annoying "features" of Mathematica is that the Plot family does extrapolation on InterpolatingFunctions without ...
14
votes
1answer
214 views
Why does LogLinearPlot sample its argument outside the specified domain?
I experience a weird bug in the function LogLinearPlot. If the input is an interpolation function, such as the one created like this,
...
1
vote
2answers
70 views
Interpolation of an upper-triangular list
I have 2d list which is upper triangular. I would like to interpolate it, but I cannot unless I set the interpolation order to 1. I tried making the list rectangular by filling the bottom half with ...
2
votes
1answer
77 views
InterpolatingFunction with growing Domain
I want to find roots of a function that is very slow to calculate (the function itself involves a bunch of FindMaxima) so I interpolate the function in a region where I think it likely the the root ...
-4
votes
4answers
231 views
Piecewise linear Interpolation between data points
Is there some sort of functionality built into Mathematica that will let me linearly interpolate between (x, y) pairs of data in an array?
Example: I have the two points (1, 10) and (2, 20), how can ...
2
votes
1answer
102 views
Join a piecewise plot
I wrote some code to get a piecewise plot which is displayed correctly. Now I'd like to join the various parts of the plot, using some kind of interpolation, to get a continuous chart even though it's ...
2
votes
0answers
148 views
How to make 3D object smooth?
This thread considers mathematical methods here to make the 3D object smooth but this question consider how to achieve the goal of smoothing a 3D object in Mathematica.
I want to get smoother ...
12
votes
3answers
231 views
How to splice together several instances of InterpolatingFunction?
I have a set of InterpolatingFunction returned by NDSolve which are valid over different (but overall continuous) domains. How ...
2
votes
2answers
88 views
Defining a function by pieces using list of interpolated functions in order to use `FindRoot`
I have two lists with the interpolated functions
...
8
votes
4answers
225 views
Numerical integration of a numeric data available as a nested list
I have some numerical data in the form of a list with the following structure: {...{x,y,z},...} defining a surface z=z(x,y) in a 3D space (x,y,z). The data came from a simulation, and I am ...
1
vote
1answer
170 views
3
votes
2answers
172 views
ListContourPlot interpolation screws up on concave set of data
I want to create ListContourPlots for sets of Data (from a physics simulation) given as Triplets {x, y, f(x, y)}. Certain parameter regions in the x-y-plane are ...
8
votes
3answers
354 views
Approximately Fit Data Without FindFit
I have some noisy data, and I'd like to analyze the derivative of the function the data approximately matches. Interpolation is normally great, but doesn't work ...
3
votes
2answers
206 views
Ways to plot interpolating functions more economically?
I am interpolating a lot of data over geographic coordinates obtained via GPS, and frequently I need to plot these interpolated functions together. For example, I may have an interpolated elevation ...
2
votes
3answers
173 views
7
votes
3answers
319 views
How to integrate functions of linearly interpolated data?
At first, consider integration of pure InterpolatingFunction.
Importing some data (works in v.9, for earlier versions one can use this link to download zipped ...
2
votes
1answer
270 views
Interpolating 2D data with missing values
I have a list (21 x 21) containing values. I want to eliminate slots containing zeros by interpolating the nearest values and overwriting the zeros. How do I use the Mathematica's ...
0
votes
1answer
203 views
Interpolating 2D data [duplicate]
Possible Duplicate:
Interpolating 2D data with missing values
I am trying to interpolate a 21x21 array of values. The 21x21 array sometimes has zero values and with the help of ...
1
vote
1answer
185 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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10
votes
1answer
220 views
How to get zeroth-order (piecewise constant) interpolation of scattered data?
Given a collection of scattered data points in 2D and associated function values,
data = RandomReal[1, {100, 3}];
we can get a piecewise linear interpolating ...
0
votes
1answer
101 views
Solve 1-D function that has 2-D interpolating functions
I need some helps on NDSolve. Here are my equations:
...
8
votes
1answer
149 views
Test if argument is inside domain of InterpolatingFunction
The documentation says In standard output format, only the domain element of an InterpolatingFunction object is printed explicitly. The remaining elements are indicated by <>
But this is not the ...
2
votes
2answers
139 views
How to create InterpolatingFunction from data?
If I have a function at a number of non-uniformly spaced data points:
youtReal[7.8]=2.0332;, youtReal[8.54]=6.24352354;..................
......... and the ...
1
vote
2answers
139 views
Doing an Interpolation through a list of lists into a single function
Suppose I have a list of lists, i.e.
list = Table[{x, x^ k}, {k, 1, 10}, {x, 0, 1, 0.05}];
and I want to interpolate each of the lists by a function using ...
17
votes
2answers
502 views
Joining and interpolating data points
I wonder what is the best practice for interpolating curves? Usually I'm using BSplineCurve and adjusting SplineWeights so it ...
8
votes
3answers
443 views
Ηow to create an interpolated CDF from its samples?
I want to use a distribution I have only aggregate statistics on, namely its CDF sampled at certain points. I would like to keep it "nonparametric" (remain noncommittal on the parametric form), but I ...
4
votes
0answers
129 views
Artifacts in Line Plot from InterpolatingFunction
I have a periodic solution from an NDSolve that is producing an InterpolatingFunction. With the default plot settings, there is not enough PlotPoints/MaxRecursion to resolve the peaks in the function:
...
8
votes
1answer
97 views
Prevent Plus from threading InterpolatingFunction
For an InterpolatingFunction $y:\ \mathbb{R}\to\mathbb{R}^2$, Plus is unaware of this, so when I do any modifications to it in ...
5
votes
2answers
165 views
How can I force points in a list to have distinct x values?
I have a list of points that may be used for linear interpolation using Interpolation and need to ensure that no two points have the same $x$ value, since, if they ...
1
vote
2answers
284 views
Interpolating a function of two variables
I am trying to create the interpolating function for a function of two variables, over a finite area. Just for consistency we can think of a function:
...
