# Questions tagged [interpolation]

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

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152 views

### The intersection of two “mesh surfaces from points”

I am a fresh user of mathematica, soo thank you in advance for your help. I would like to get a list of points (x,y,z) at any interval (eg every 0.05 by x and y coordinate) which are created by ...
240 views

### FunctionInterpolation over an open interval

I'm trying to obtain an arc-length parametrization of a spline curve as per https://mathematica.stackexchange.com/a/8456. To do so, I need to calculate partial derivatives of such curve and then ...
2k views

### How to calculate the control points of a Bézier curve?

To plot a BezierCurve in Mathematica, I need control points. But, I do not know the control points; I only know the points through which the Bézier curve passes. ...
297 views

### How do I find a function to fit these criteria?

I want to find a smooth continuous function f[x] that satisfies the following for real values of x: ...
110 views

### Efficiently fill sparse matrix involving BSpline

Context In order to implement regularised fitting in 2 or 3 dimensions (as is done say here) using BSplineBasis one needs to evaluate a basis over a set of data. ...
153 views

### Derivative of an interpolation function is noisy

I have a set of numerical data of 1501 points, in the form of $\{x_i,a_i\}$ which I uploaded to here and here. I need to compute the numerical derivative of this data. In particular, I need the ...
79 views

### Deal with noise and missing points in data [closed]

I have run a simulation which has resulted in some bad data (see graph below). What would be the best way to detect and interpolate the missing points in Mathematica (i.e. remove the noise)? Raw ...
314 views

### What is wrong with this code? (Usage of FunctionInterpolation and how to make code efficient)

I am trying to create an interpolation out of a function that comes from an improper integral. The end goal is to make a 3d plot over a specific region. Specifically, I have the following code: ...
74 views

### How to calculate partial derivative of an InterpolatingFunction in two variables

I have a InterpolatingFunction from a list of complex data $j(x,y)$ in two variables $x$ and $y$. I need to evaluate this equation $( x ∂j/∂y - y ∂j/∂x )$. ...
90 views

### A problem when interpolating the data

I have some data in a form data = {{x,y,f[x,y]},...}, where f[x,y] takes only positive values. When I try to interpolate it, <...
77 views

### Find region of given value for linear Interpolation function

Summary: How do I find the (possibly disconnected) region(s) where a linear interpolating function is between two specified values? Example: ...
4k 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 ...
1k views

### How to speed up integration of interpolation function?

I have a list of data, and I interpolate it to a function. Then I need to do an integration with the interpolating function. But I found that the speed is unacceptably slow. My data is here (a little ...
230 views

### Interpolation of data

Consider a set of data points ...
227 views

### How does this Mathematica code work?

I am trying to work with a simulation of Brain Tumor growth and I was fortunate to get a very great example at http://community.wolfram.com/. However, I need clarifications on some of the code. I ...
104 views

### Does ElementMeshInterpolation work for arbitrary orders?

Mathematica will not, in general, do arbitrary order interpolation on unstructured grids: ...
73 views

### When I use Plot to plot an interpolating function which is the solution of a big ODEs solved by NDSolve,I found it takes a long time

I'm a Chinese student.I can't speak English very well.If there are any mistakes,please forgive me. I use NDSolve to solve a big ODEs. ...
6k views

### Finding x given y from an interpolating function

I would like to put a dot on the point of a curve that has a specific y value but I don't know the x value. A simple example of my code is ...
405 views

### How to easily find the coefficients of a cubic polynomial and its plot for the given 4 points

Given 4 points as points = {{0, 4}, {1, 0}, {2, -1}, {3, 0}};. I want to find the coefficients of ...
150 views

### How can I obtain the domain of a resulting Interpolating Function?

I have a problem with obtaining the domain of resulting Interpolating Function in my calculations. I want to solve the following differential equation ...
100 views

### Several errors with InterpolatingFunction [closed]

I'm getting some error messages that don't make sense. Apologies, as the code is somewhat complex. Basically what I'm trying to do is solve a system of differential equations, then fill a table with ...
398 views

### Export to PDF: DensityPlot & AllowRasterization->False

How to get production-quality vector graphic exported from Mathematica that looks like what is plotted in Mathematica. Example code: ...
215 views

### Plot with different colors the results of an NDSolve with vector solution

Consider the following toy example: ...
127 views

### Contour lines in ListContourPlot with InterpolationOrder 0

I have a dataset and would not want Mathematica to interpolate at all while plotting the contours. This is because the data contains essential binning information and the "steps" in the contour must ...
82 views

### Solve an ODE involving an Interpolating function with Mathematica

Using Mathematica, I want to solve an ODE of an Interpolating Function. First I solve the ODE obtaining the function y[s] (or Y[s]) ...
139 views

### Curve fitting, Polynomial [closed]

I have a data set in such a manner ...
62 views

### Parallelize Slow on Interpolated Functions

So I have an FEA solution from COMSOL and I import the mesh and values at the vertices to create an interpolation function. ...
91 views

### Shifting the domain of an interpolated function

If I interpolate a list f=ListInterpolation[{1,2,3,4,5,6,7}] the result is in the domain {{1,7}}, so something like ...
180 views

### Interpolation order reduced to 1 due to unstructured grid error; yet proper syntax?

I am attempting to do a second or third order interpolation on a grid of 2D data with 1D output; i.e. a scalar function on the complex plane. However, when attempting to do: ...
276 views

### Derivative of an interpolating function

I have an interpolating function (which comes from an integral that cannot be done analytically), it looks nice and smooth: However, since what I need is the derivative of this function, it is not ...
61 views

### Is there a way to gather the points used in a Plot and generate a function that passes through those points?

like the title says: is that possible? In my case, I have a plot of an integral that is evaluated numerically. Maybe using Interpolate with the points used by mathematica to draw the graph or ...
110 views

### Interpolating and plotting from a list

I have a dataset in this form (but much bigger of course): ...
138 views

I have a series of data points describing the boundary of some region. Using ListCurvePathPlot, I have an easy way to get a nice curve interpolating this boundary (...
58 views

### Plot interpolating function depending on free variable inside manipulate

I create an interpolating function which depends on some free variables. I then want to plot it inside a manipulate, but my output is empty. What am I doing wrong? ...
204 views

### ListContourPlot Interpolation

I plotted a data file with ListContourPlot and I have this result: ...
68 views

### Non-square data array distorted when using InterpolationOrder->0 in ListDensityPlot

I am trying to fit a list {{x1,y1,f1},{x2,y2,f2},...} with ListDensityPlot. The tricky part is that for a fixed x, the list does ...
213 views

### Finding the $y$ value of an interpolated function given an $x$ value

I am trying to interpolate my dataset, which is a list of points. Thus I have two interpolated functions of my x data and y data: ...
236 views

### Interpolating a list of points to find precise x(f) values

I am trying to get Mathematica to interpolate a list of points so that I can find precise x values x(f) that won't have a corresponding data point. Here's what I've tried: ...
108 views

### Verify polynomial equation for set of 3D data [closed]

Goodmorning, I mean to this link: Find polynomial equation for set of 3D data I tried to verify the result, namely if the interpolation is correct, but I found something that I don't understand. I ...
1k views

### Find polynomial equation for set of 3D data

data was given in columns in the order {y, x, z}, with y dependent on x, z ...
144 views

I have a fairly complicated scalar analytical function of 3 variables that appears to be quite incompatible with SliceContourPlot3D (I shut it down after a few ...
345 views

### How to take derivative of the argument of an interpolating function

I am trying to plot the derivative of the argument of an interpolating function u[t, x] with respect to $x$. Here, u[t, x] is ...
74 views

### Loop command in Interpolation

I have a following interpolation function A[x,y] defined below. The variable y has some fixed range which is different for each <...
10k views

### How do I prevent NIntegrate::inumr errors within other functions?

I believe this question is best illustrated with a simple example. If I run FunctionInterpolation[NIntegrate[a + b, {a, 0, 1}], {b, 0, 1}] I get errors of the ...
706 views

### Interpolation of Discrete 3D Vector Field

I have a vector field with discrete values and I want to interpolate these values to create a differentiable vector field. I have matrices which give the vector values of the velocity - $vx, vy, vz$....
128 views

### This PDE freezes Mathematica

I have a problem when I try to solve this PDE: ...
45 views

### How to Integrate a function of an InterpolatingFunction?

Let u consider the case (given in Mathematica documentation as an example) ysol = NDSolveValue[{y'[x] == y[x] Cos[x + y[x]], y[0] == 1},y, {x, 0, 30}] So, you ...
184 views

### How to find max and min values

Need to find max and min values like on pic. I am wondering how I could determine max and min values of oscillations ? How could I find these values: My code: ...