# Questions tagged [interpolation]

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

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### NDSolve going outside of the range of the interpolating function

I am trying to solve a differential equation that contains some interpolating functions as input, and for reasons unknown to me I am encountering an error which makes Mathematica use extrapolation. I ...
68 views

### Evaluation of Mod of InterpolatingFunction prevents discontinuity processing by Plot

While trying out @MichaelSeifert's answer to Eliminating Discontinuities When Using Mod with NDSolve and Plot for Oscillators, I came across this odd behavior. Depending on how an ...
114 views

### Approximating decay rate of an amplitude and frequency of an oscillating function

I have an InterpolatingFunction constructed from a discrete set of values obtained by numerical methods. Let's denote it $f(x)$. The function demonstrates an ...
125 views

### Creating a numerical table of values from an interpolating function resulting from NDSolve [closed]

I am trying to carry out point "Implementing Map" on this paper Interstellar wormholes however I am using my own equations not those given (only the same method). Part 1 I am trying to create a ...
360 views

### Complex continuation of an interpolated function

Context I have a complicated real function defined implicitly by a series of imbricated numerical integration. I need to make a continuation of this function for a complex variable which is easily ...
104 views

### Merge pairs in a list that have the same 1st element by averaging the the 2nd elements

I'm trying to do interpolation on a large list of data of the format {{x1, y1}, {x2, y2}, {x3, y3}, ..., {xn, yn}} that is exported from a simulation. ...
441 views

### Repeated interpolation for 3D unstructured grid -> Optimization

Trying to perform mesh-to-mesh 3D interpolation on unstructured grid. Mesh size is about 200k nodes. Painful thing that interpolation shoud be repeated ~1000 times (different thermal map) on the same ...
3k views

### Exporting interpolating functions to excel

I have a question about exporting an InterpolatingFunction to Excel. I checked the forum, but I still couldn't completely understand how to solve my problem. Could ...
148 views

### Pass arguments to a function within a function within a function

I want to perform an integration of f[w,t,kx,ky] over t for several different functions f. ...
158 views

### NIntegrate InterpolatingFunction Kernel Crash

I would like to Investigate if the edges of this 2D heat equation are insulated by the Mathematica assumed Neumann conditions. ...
2k views

### ListContourPlot interpolation fails if x and y axes have different scales

To summarize what is below: ListContourPlot doesn't work when the domain has different x and y scales (fails when x/y~10^4, which seems surprisingly small). Is it possible to call ListContourPlot on ...
1k views

### Interpolation on a regular square grid spanning a triangular domain

Bug introduced in 10.0 and fixed in 10.1 Context I am trying to identify contours of a function which is sampled on a cartesian grid within an irregular (triangular) region. Here is the data <...
106 views

### Integrating an interpolating function: Hermite vs. BSpline

I have an interpolation through a list of points, which I need to integrate. The minimal working example looks as follows: ...
105 views

### Solve from interpolation function

I have the following list and its interpolating finction x1: point={{0., 0.}, {0.2, 1.}, {0.25, 1.5}, {0.3, 1.}, {0.5, 0.}};x1 = Interpolation[point] I would ...
98 views

### How to evaluate the “Domain” of a Parametric Function?

In a simple example I try to calculate the time the solution x[t] passes a second time x[t]==1. ...
106 views

### NDSolve and interpolating function

What could possibly went wrong in my code? Basically, I am solving the differential equation $\textbf{ode}$ using $\textbf{NDSolve}$. But mathematica says, NDSolve::mxst: Maximum number of 10000 steps ...
27 views

### Why do I keep getting an interpolation error?

Whenever I run this code, it does not seem to be evaluating anything past the Evecs. There are other definitions/parameters involved in running the code. I am just not sure why it keeps saying "first ...
36 views

### How to close the contourplot3D from top?

I received a very nice solution by Chip Hurst to make my 3DContourPlots smooth and closed in here. Now I have another problem that is simpler but I still want to know the ideas of the others. The data ...
29 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 ...
39 views

### Interpolation of a list defined on a region

I have a three-dimensional table (each element has the form { x, y, f( x, y ) }), and the x, y coordinates spans a region of a parallelogram. If I do a list contour plot of the data, it gives the ...
218 views

### Interpolation function

I am facing a problem in getting a smooth plot of following data. ...
110 views

Writing: ...
139 views

### Recycling solutions of multidimensional NDSolve

Dear wolfram community, I hope my problem is clear and easy to solve. I have already solved the following heat equation over a domain: ...
72 views

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### Continuous non-piecewise equivalent of smoothstep function?

I have a smooth step function given by the piecewise function ...
72 views

### Use InterpolatingFunction in differential equations involving derivatives and integrals of the InterpolatingFunction [duplicate]

I solved a problem of solid mechanics, 11 unknown components of displacement functions, i.e., ut0[x, y], wt0[x, y], wc0[x, y], .... ...
106 views

### Basic 3D Interpolation Failing

I've seen a few other posts asking about the "unstructured grid" error in Interpolation. Here's a minimal (non)working example of the issue: ...
564 views

### How to fix broken InterpolatingFunction?

Bug introduced in 8.0 and fixed in 9.0.0 I have an InterpolatingFunction based on irregularly-gridded data, like this: ...
273 views

### Deleting mesh elements from a mesh

I am trying to make an interpolation function over my data. The points I am selecting make an unstructured grid, so I am following through the steps in the documentation "ref/message/Interpolation/...
136 views

### Defined Mesh Coordinates are Outside of Data Range for Interpolation Function

This relates to a previous question I had about formulating an interpolation over an unstructured grid. A new issue I am running into (in this test example) is that some of the coordinates that are ...
1k views

### Interpolation function error: Interpolation::femimq and Interpolation::fememtlq

In Mathematica 10 the following command ...
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### Derivative of an interpolated function on an unstructured grid

I'm writing my own FEM Poisson equation solver in C++ and I'm using Mathematica as a benchmark - currently it seems that my program outputs a correct solution, however I want to check whether the ...
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### InterpolatingFunction gives different result when plot [closed]

I solve a series of ODE equations by NDSolve({t,0,200} is the region), it gives results in the form of ...
146 views

### 2D interpolation of function with dependent interpolation border

My problem is to compute $$\int\limits_{x_{min}}^{x_{max}}\int\limits_{y_{min}}^{\sqrt{x^{2}-a^{2}}}W(x,y)g(x)\ dx\ dy$$ Because $W$ have highly oscillatory 2d complex numeric integral inside, dumb ...
76 views

### Interpolation in a data set [closed]

I have the given dataset dat1 = {{0, 0, 1, 10}, {0, 0, 2, 5}, {0, 1, 1, 4}, {0, 1, 2, 3.5}, {1, 0, 1, 0.8}, {1, 0, 2, 0.6}, {1, 1, 1, 0.4}, {1, 1, 2, 0.2}} In ...
78 views

### Numerically integrate over an Interpolating function [closed]

I would like to integrate over an interpolating function, which itself is the output of NDSolve in the following code. Unfortunately, I get an error code, saying ...
686 views

### Convert BSplineFunction into two Interpolating Functions

Is there a way to decompose a BSplineFunction output into two functions x[t], y[t] ...
208 views

### Interpolation function evaluation and timing

Lets define two identical functions $f$ and $g$ in a slightly different way ...
124 views

### Getting error 'InterpolatingFunction::dmval' while trying to find the maximum of an interpolated function

The code I used is ...
204 views

### Find interpolation with derivatives at some points

I am trying to find out how to find a good interpolation of a periodic function I have from some data points. The only problem is that I need to make sure that derivatives at the starting and ending ...
78 views

### color interpolation using interpolating functions on a quadrilateral

How can I use the interpolating functions I constructed for the four nodes of a quadrilateral to use as parameters to smoothly paint the edges of the quadrilateral when 4 different color values are ...
115 views

### Defining the boundary conditions of a PDE

I'm first time use Mathematica and here is my trying of solving equation ...
69 views

### How to color the nodes of a quadrilateral polygon

say we have the list of points a = {{1, 1}, {2, 1}, {2, 2}, {1, 2}, {1, 1}}，it is a simple square, how can we make color the nodes( in which that the nodes and the ...
67 views

### Interpolation error of InterpolatingPolynomial[]

this is my first post so if I have any error while writing this, I'm sorry. I had to do a polynomic interpolation for one of my lab experiments, and I need to get the error from it in order to ...
48 views

### The intersection of two “mesh surfaces from points” which are not convex

After solving the problems with determining the intersection of two mesh surfaces I came across an additional obstacle. Link to the previous question enter link description here Unfortunately, I ...
577 views

### FindMaximum of Interpolated data set

Probably a fairly easy one; but I'm drawing a blank I would like to find the maximum of an interpolated data set. I've tried using ...
66 views

### how to color edges of a convex polygon,say a square, using interpolation with respect to the color in Mathematica

How do I color edges of a convex polygon, say a square, using interpolation with respect to the color (to form parametric polynomials) in Mathematica, so that the colors displayed on the 4 edges would ...
889 views

### Quirk in VertexColors interpolation when displaying Polygon

When using VertexColors, the docs state: The interior of the polygon is colored by interpolating between the colors specified by ...