# All Questions

206 views

### FindFit with parameters which are simultaneously in initial conditions

I have RLC circuit. I would like to find R and L by using FindFit, but L is in initial condition and I have problem with it. Could you help me ? ...
14 views

### Numerical derivative step size

I am trying to perform a numerical derivative of some function using 'ND'. I want to know if there is a way to set the step size of differentiation to the specific value I want. Can this be done ...
42 views

### How to define Goodstein's sequence?

There is an amazing and counterintuitive theorem: For all $n$, there exists a $k$ such that the $k$-th term of the Goodstein sequence $G_k(n)=0$. In other words, every Goodstein sequence ...
118 views

### ParametricPlot3D won't show [closed]

I want to see the image of a tube made from a space curve. I define the surface using Frenet-Serret frame but the software does not show me the plot. What might be wrong with my code? Thank you.
239 views

### Law of Cosines to determine angle change along spiral

The Spiral I'm trying to place circles along the outside of an Archimedean spiral. Shown below: ...
309 views

### WordData for other languages

Mathematica already includes dictionaries for a lot of languages. What I am looking for is a handy semantic/grammatic database for Hungarian, just like WordData for ...
961 views

### List all financial Assets data conditionally

I would like to get all the Financial Data that Mathematica respecting those constraints : The assets for which there are at least 20 years of daily price quotations. Or that have s price for each ...
64 views

### How to create a Text with certain size given in a specified way?

I have some text and I would like to show them in some order in Graphics, but I want them to be in certain size so it will looks good. (Primarily for improving my ...
22 views

### Loss of scale factor when reading/recording/rereading data in a WAV file

I use recorded data from an acquisition system in a wav file containing 6 channels, all data are encoded with 2 bytes in Integer 16. I can Import the *.wav data file and get all data in a Sound object ...
29 views

### Evaluating summations involving Fibonacci numbers in terms of Fibonacci numbers

There are many summations involving Fibonacci numbers which Mathematica 10.4 is able to evaluate directly in terms of Fibonacci numbers. For example, Mathematica evaluates the summation given below as ...
1k views

### Plotting a 2D shape along a 3D parametric function curve

Say I have a 3D curve that is parametrically defined. How would I be able to plot shapes like figure 8's whose centers are aligned along the 3D curve? Say the curve was: ...
118 views

### Creating a tube with custom caps

I need a tube with only one end capped. I can do this relatively easily with: ...
52 views

### Deleting circular regions from a larger Circle

I am trying to determine how the Dirichlet eigenvalues of the Laplacian of a circular region change. I would calculate the principal eigenvaluen of this image, and gradually decrease the radius of the ...
1k views

### Mathematica style guide?

I encountered this site today https://code.google.com/p/google-styleguide/ regarding the programming style in some languages. What would be best programming practices in Mathematica, for small and ...
374 views
+100

### How to produce the ILU0 or ILUT as stand-alone procedures on sparse matrices?

Mathematica uses the ILU0 procedures automatically to precondition large sparse linear systems; e.g. ...
21 views

### Implementing four-fermions operators on FeynRules and FeynArts

I am trying to implement operators of the form $$\bar{q}_L \gamma^\mu T^A q_L \bar{q}_L \gamma_\mu T^A q_L$$ where T^A are the SU(3) generators and $q_L$ is the Electroweak SU(2) doublet. I use ...
137 views

### How to generate specific function using BSpline command?

I want to generate an approximation function that fits a curve to points. My goal is to obtain an actual formula. Is this possible with BSplineFunction? Using the ...
34 views

### resetting keys after using GroupBy to total

I think I saw a question like this on the site some time ago, but can't find it. I'm using GroupBy on a list of Associations to ...
65 views

### Treating the output of a plot function as a graphics object, changing the opacity

I want to treat the output of a plot (DensityPlot specifically) as a single graphics object and reduce its opacity. Something like: ...
313 views

### Simplify results further

I have an extremely long result in polynomial form following some matrix operations. However, given the symmetry of the problem, I can safely say that the solution will reduce much further than is ...
26 views

### ListVectorPlot contour lines

I dont know why so many plot functions lack the option to display contour lines (judging by the search result for [plot function] contour lines) but ListVectorPlot is among them. If I have an array <...
27 views

### How do i get a step by step solution about aan inverse z transform ? [on hold]

Good afternoon I'd like to know how do i get the step by step solution of those types of exercises.
232 views

### Solve a nonlinear PDE equation with a Neumann boundary condition

I am trying to use Mathematica 10 to solve a PDE $$u_t=u_{xx}+u_{yy}+u(1-u),$$ in the unit disk $(x,y) \in D=\{(x,y):x^2+y^2<1\}$, with the Neumann boundary condtion \frac{\partial u}{\partial n}...
27 views

### Set a minimum threshold value for a function

I have defined the following function in Mathematica al[z_] := (a/((1 + a*(b/(2 Pi))*Log[z/Mz]))) (a and ...
18 views

### {Protected, ReadProtected} System symbols give “Set::write: ”Tag * in *[v_] is Protected" on first try

Run Quit, then Unprotect@AbelianGroup; AbelianGroup[v_] = 0; Protect@AbelianGroup; where instead of ...
161 views

### Selecting points inside a closed curve

Let's create a rather dense grid of initial conditions ...
109 views

### Mathematica 10 enables discrete GPU

When the kernel is running, the discrete GPU is enabled automatically and battery life plummets, even though my code uses no CUDA or OpenCL functions. Is it possible to prevent that from happening? ...
164 views

### More issues Integrate, NIntegrate, FindRoot

I'm trying to solve a system of 3 non-linear equations using FindRoot and Integrate. If I start FindRoot[] close to the right answer, it works well but returns a bunch of error messages first. ...
1k views

### Filtering beat-to-beat heart rate data

From an experiment, I have a dataset of beat-to-beat heart rate data: a list of the time between each heart beat in [ms]. The data is measured using an infrared optic sensor at the finger tip. The ...
34 views

### What is the default Lighting in 3D graphics?

The default value of the Lighting. This typically uses "Standard", with several coloured lights, or ...
49 views

### Unexpected behavior of DiscretizeGraphics

As this code,we can visualize the "Test text" Graphics[Text[Style["Test text",20],{0,0}],Axes->True,AxesOrigin->{0,0}] I try to use ...
21 views

### Multivariate integration of a compicated expression

I have an expression in multiple variables that is something like ...
30 views

### Table giving error Part::pkspec1: [on hold]

I am evaluating the following expression: ...
88 views

### Inflection point and curvature

Through a coordinates list and then interpolating them I got a $f[x]$. ...
33 views

### Visualization of tracks of objects in images by superposition

I have sets of images (each contains about 3000 images where many objects are seen, each image is 4 Megapixels large, format is 8bit, gray scale, png). To get an impression about the trajectories of ...
240 views

### Gillespie Stochastic Simulation Algorithm

The Gillespie SSA is a Monte Carlo stochastic simulation algorithm to find the trajectory a dynamic system described by a reaction (or interaction) network, e.g. chemical reactions or ecological ...
59 views

### About changing the values of global parameters within a function [on hold]

For the code below: a = 1; b = 2; f[c_, d_] =: Module[{e, f, g, h, ...}, ...]; I have references to a and ...
105 views

### How to remove parts of an expression [on hold]

I have an expression where terms Transpose[R].R appear. R is a matrix with the property Transpose[R].R=IdentityMatrix[3]. How ...
42 views

### Chains of approximate numeric equalities

Mathematica considers two numbers equal if "at most their last seven binary digits" differ. For example: ...
21 views

### Using the TwoAxisListPlot Package and Show Together

I am using the TwoAxisListPlot package to generate a plot with two y-axes (obviously!). I have made a NonlinearModelFit to one ...
26 views

### How to open and use the blackbody radiation program in Mathematica [on hold]

I am trying to open and plot the blackbody profiles for four different temperatures which are (2000,1000,400,100)K. The y coord runs from 10^-4 to 10^6 and the x coordinate runs from 10^-10 to 10^-4. ...
112 views

### Deleting vertices from Graph and preserving Structure?

My goal is to remove vertices from graphs (and the edges from them) and then take GraphComplement to find out cut sets in graphs with sink and source such as here. So How can I delete vertices from a ...
11 views

### plotting quaternary [duplicate]

For more information to draw tetrahedron like figure for my data i again insert my data. I have 4 sets of data in 4 axis (x1,x2,x3,y) x1=0.0557 0.0575 0.0613 0.0656 0.0615 0.0448 0.0488 0.0595 0.0654 ...
28 views

### Multivariable non-linear fitting

I have a function called "C" that I know it depends on 6 variable. I have a set of data points, 6 rows by 9 columns, in which in each row only one variable is changing and the rest of the variables ...
106 views

### To deal with infinity in NDSolve

Edit: I modify the question so that it uses exactly the same expressions I am having difficulties. I just started to learn to use Mathematica, and was trying to obtain an inverse function. Helpful ...
72 views

### Bug in the “PrincipalValue” method of NIntegrate?

Update As pointed by Emilio Pisanty, one should pay attention to EvaluationMonitor to monitor principal value integration. I update the codes, and find some more ...
45 views

### How to set UnitSystem permanently

I would like to set the system of units (\$UnitSystem) permanently to "Metric". I know that I can do ...
1k views

### 1D Euler equations (fluid dynamics) with NDSolve

Is it possible to accurately solve the 1D Euler equations in Mathematica using NDSolve? For example, let us consider the problem given here: http://www.csun.edu/~...