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0
votes
2answers
48 views

Better fit for points with exaggerated deviations

I used the InterpolatingPolynomial function to get a polynomial that meets my points. But I noticed that there is a deviation in the final intervals. ...
4
votes
2answers
76 views

Plotting perpendicular lines to a contour plot (electric field from equipotential curves)

I'm currently working on a experiment about Electric Fields and Equipotential Curves. The problem is that I want to plot (estimate) the curves of electric field using the fact that every one of these ...
1
vote
1answer
51 views

Regression to fit data with an integral equation

I have a set data and I know that this data are best fitted by the following equation, assuming that f($\tau$) is a log normal distribution and $M_{eq}$ = 1.5: $M(t,\tau)= M_{eq} \int (1-e^{-t/\tau}) ...
2
votes
2answers
116 views

Fitting two-dimensional data

For this question, I cannot use random sample data. So the actual data can be found here. The data file contains three columns, where the first two are the coordinates $(x,y)$, while the third is the ...
3
votes
0answers
48 views

BSpline vs natural spline [closed]

The BSpline in mathematica is defined mathematically here. These BSplines constitute basis for any Spline. But how do I define natural splines in mathematica, i.e. splines that are linear left of the ...
0
votes
1answer
64 views

Problem with fit

I am trying to find a proper matching function for the following data set: ...
3
votes
1answer
99 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 ...
2
votes
2answers
108 views

Interpolator surface

Writing: ...
0
votes
1answer
150 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 ...
3
votes
0answers
78 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 ...
2
votes
2answers
131 views

Curve fitting, Polynomial [closed]

I have a data set in such a manner ...
0
votes
2answers
101 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 ...
1
vote
2answers
93 views
2
votes
1answer
263 views

Building a 2D function by combining 1D functions

I have six 1D continuous functions that I want to use in order to find a 2D function. Each of these 1D functions has to be placed at a unique angle $\phi$ w.r.t the $x$-axis as given in the image ...
1
vote
0answers
67 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 ...
1
vote
1answer
67 views

Line Equations from Interpolated Data

I have an interpolated line from a series of measured data points. Is there a way I can get Mathematica to output an approximate equation for the interpolated line? For example: From the ...
1
vote
0answers
63 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?...
0
votes
0answers
46 views

Generating the best-fit formula for given data

I have three independent variables and one dependent variable, I want to generate a new formula for calculating the dependent one using the three independent ones, I have the data series like below: <...
0
votes
2answers
255 views

Fitting a curve [closed]

I want to find the curve that would fit the following data: ...
-2
votes
1answer
449 views

Create a spline function to interpolate a 3D surface [closed]

Here's my problem, I have an spreadsheet that contains data, a 202x202 matrix with x,y and z coordinates. The objective is import the data to mathematica, and then I need to create an interpolation ...
6
votes
2answers
321 views

How to derive/interpolate a polynomial f(x,y) from several discrete polynomials f(x)?

I have 7 discrete degree 3 polynomials $f_i(x)$. Each of them represents a snapshot of data from an experiment and fits this data quite well. This graph depicts the 5 largest of the 7 polynomials: ...
18
votes
2answers
2k views

Inflection point and curvature

Through a coordinates list and then interpolating them I got a $f[x]$. ...
1
vote
2answers
150 views

Quartic function from data [closed]

I am studying something about interpolation. I have a function that is a power x function (f[x_]:=17000 x^-1.85). From this function I got a list with coordinates ...
1
vote
1answer
176 views

Importing Data to interpolation

I have an external file in extension XLS with looks as follows: This file can be obtained by the link below: Velocidade Angular With certainty this file is generating a list inappropriate for the ...
0
votes
1answer
147 views

Interpolating data while imposing the behavior of a cumulative distribution function

I would like to interpolate a data set which represents a curve of an empirical cumulative distribution function (CDF). Hence, the y entries are between 0 and 1, continuous and non-decreasing, and at ...
1
vote
1answer
100 views

Predicting the initial conditions of orbits inside a closed curve

I have a data file containing the four orbital element $(x,y,p_x,p_y)$ of a two-dimensional closed loop orbit. Note that the exact implicit equation of the orbit is not known. The plot of the 2D ...
4
votes
2answers
771 views

Mathematica Interpolation or approximation

I have lists of points X and Y. {1212,1216,1217,1219...}, {1,2,3,4,5,6...} I combine ...
3
votes
0answers
167 views

How to find the best fit for given input data? [closed]

I have the following data: ...
5
votes
1answer
719 views

Intersection of a ListPlot3D surface with a plane

I'm trying to use Mathematica to analyze some physics data from an experiment, more precisely, I have to fit a 2D data series with a one dimension function. At the moment I'm able to load and plot ...
0
votes
1answer
108 views

How to fit this data to be used in NIntegrate later?

I have a list of data points that resemble a chi-squared distribution (long tailed gaussian) that I am having trouble fitting or finding an equation with. The goal is to use the fitted equation in an ...
3
votes
1answer
229 views

How do I find out what a Mathematica function is doing (which numerical method it uses and how)?

Long story short, I am working on a project which entails fixing a bug I have found in Mathematica (8 and 10). In general, I would like to know what a specific Mathematica function is actually doing ...
2
votes
2answers
309 views

BSpline or other curve through arbitrary ordered sequence of two-dimensional points [duplicate]

How does one create a BSplineCurve or other smooth curve passing through each point in an ordered list, where the curve may be non-simple, i.e., can double-back ...
14
votes
3answers
1k views

2D smoothing spline interpolation

Does Mathematica have 2D smoothing spline interpolation built in? I requires an interpolation method with smooth first derivatives and cubic bivariate splines fulfill this nicely. In python I would ...
14
votes
1answer
1k views

Curve fit based on minimal data

Inspired by the fantastic answers here and here, I would like to ask a questions along similar lines. I have 6 curve types that follow these rules: Type A: If point 1 is positive and point 2 is ...
3
votes
3answers
314 views

Zero-order interpolation not going fully around

Connected to this question, I want to do a zero-order interpolation of a bunch of datapoints which is periodic. The code I use is as follows: ...
1
vote
1answer
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 ...
1
vote
0answers
787 views

Interpolating function as a model in Mathematica's procedures for fitting

Is it possible to use interpolating function with parameters as a model for NonLinearModelFit (and other integrated methods for fitting)? Similar question was ...
7
votes
1answer
2k 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 ...
1
vote
1answer
816 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. ...
14
votes
1answer
2k views

Fitting a spline to data with FindFit?

I am trying to find a function that fits my almost linear data. A high order polynomial model has too much residual. So I was hoping to use Mathematica to fit splines to the curve. This is what I ...
7
votes
2answers
660 views

How to find Matano plane

I have discrete collection of data points (10 to 10^4). I want to describe them by a continuous function and find a x value z, ...