2
votes
1answer
70 views

Non-autonomous Dynamical system Sliding mode controller Error

This code is a simulation of a sliding mode controller of a non-autonomous dynamic. When I use ArcTan in input, I receive an error. ...
2
votes
2answers
113 views

Aligning Density an Contour Graphics

In radiation therapy, we display radiation dose as an isodose contour plot overlain on density plot describing the patient geometry (CT data). Here is a simple example (the material grid is voxelated ...
3
votes
3answers
84 views

Orderless storage of tabulated function values

I would like to elaborate on my previous question Function of arguments given in non-fixed order and a relevant related one Best practice of passing a large number of parameters to functions I find ...
1
vote
1answer
80 views

Ndsolve problem with Sign

Using Sign(...)] in the formulation of my system of ODEs is causing an error that I don't know how to correct. If I use (...) in ...
8
votes
2answers
368 views

Getting a correct custom legend for contourplot?

I am having trouble making a custom range for a legend in ContourPlot since the legend doesn't "talk" to the PlotRange and ...
6
votes
3answers
484 views

Locators in Manipulate not moving properly

I thought a simple Mathematica kerning machine (for adjusting the space between characters) would be interesting, but I'm having trouble with the locators. (There are a number of other questions ...
3
votes
3answers
144 views

How I can count multiplications in an experssion?

Next task to complete: Count *-symbol in such expression as a + s^2*b - c/y + o^3 + n*m*u (in this case count of ...
1
vote
0answers
236 views

Solution to heat equation with Neumann boundary conditions and lateral heat loss

I am conducting an experiment on heat conduction in a copper rod. To do so I am using a thin copper rod with several temperature probes, then I am going to compare the data with a solution to the heat ...
5
votes
3answers
500 views

What is the best way to write a polynomial in the Bernstein basis?

The Bernstein basis of polynomials of degree $n$ is the set of polynomials of the form $$\binom{n}{k} t^{n-k}(1-t)^k$$ where $0 \leq k \leq n$. What is the best way to transform a given polynomial ...
3
votes
1answer
293 views

How to sample n frames from a movie file?

I'm looking to import 100 image frames from an mp4 video file at roughly evenly spaced intervals. As $ImportFormats shows, Mathematica can handle Movie files: .avi, .mov, .qt, .flv Multiframe ...
13
votes
3answers
6k views

Increasing the thickness of line in plot legend

I've been using the shiny new legends in V9 for my plots. However, I usually increase the Frame/Axis ...
3
votes
3answers
303 views

Hypergeometric function with a matrix argument

I am looking for the evaluation of a Hypergeometric function with a matrix argument as for example in Koev and Edelman or as showcased in this Wikipedia article. From what I understand from ...
1
vote
2answers
177 views

How can I import a table from a Wikipedia page?

I'm trying to import this table from a wikipedia page containing the list of lunar missions into a Mathematica as an Association. Here, I'm trying to use the new ...
0
votes
0answers
56 views

Is it possible to change default $HistoryLength [duplicate]

By default $HistoryLength is set to \[Infinity]. This is often unnecessary and can cause unecessary memory usage. I can of ...
3
votes
1answer
751 views

Specific Mathematica algorithms, for example LU Decomposition

Where I can find detailed information on algorithms used by Mathematica, especially for numerical methods. The Manual doesn't seem to iclude specifics in most cases. For example I get a different LU ...
0
votes
0answers
63 views

Why is PolyLog[] giving weird answers for ordinary values? [duplicate]

Possibly related to this question, but it seems slightly different: Strange behaviour of PolyLog Function Wikipedia says that for real s, z<1 should be real. So I was confused when MMa returned: ...
3
votes
1answer
104 views

Stopping NDSolver at time of error

I am using NDSolver and WhenEvent to solve a system of differential equations. I get this message: ...
0
votes
0answers
40 views

Please explain this unexpected code snippet behavior [duplicate]

Consider a function that maps a complex function z->f(z) to it's multivariable counterpart (x,y)->f(x,y) ...
2
votes
1answer
605 views

Creating hexahedral finite elements in Mathematica

Is it possible to do FEM using hexahedral elements in Mathematica? If it possible, is there any help to do that?
3
votes
2answers
103 views

Demonstration Confusion

What is the proper way to open a Demonstration in Mathematica so that the code is visible and can be evaluated from the Evaluation menu, as though I had created it myself? Explanation: When I ...
2
votes
1answer
158 views

gaussian integration

I'm new on Mathematica and I am an engeneer with only a little base of numerical computation. I have to integrate a trigonometrical function numerically with a Gauss integration. The function is: ...
1
vote
1answer
111 views

Matrix multiplication for higher dimensional matrices [duplicate]

I have a matrix like this (myb1): I would like to get the matrix multiplication of each of the submatrix to itself. For example the first 2x2 matrix $\begin{bmatrix}1 & 2\\1 & ...
2
votes
2answers
234 views

Finding integral points on a surface

Suppose I have a dimension formula (for a Lie algebra representation) that is as follows: $$ d(a,b) = {(a+1)(b+1)(a+b+2) \over 2} $$ Now consider the surface $F(a,b,n) = 0 = d(a,b) -n$ where $n \in ...
2
votes
1answer
157 views

Gradients of the NDSolve PDE solution

I would like to understand, how to obtain gradients of the PDE solution obtained with NDSolve. To be precise let us consider a Laplace equation from one of the examples: ...
1
vote
3answers
327 views

Trouble using Manipulate and NDsolve for coupled ODE's

I'm aware that there are a few threads on the topic of solving coupled ODEs using NDSolve and Manipulate. Based on those, I ...
4
votes
1answer
321 views

Use FEM Solver for System of Nonlinear PDEs with Nonlinear Coefficients - Reaction-Diffusion

I am trying to solve a complex transient reaction-diffusion problem numerically in 2D. Let's take a simple system to start, say $$ A+B\rightarrow C \\ C \rightarrow A+B $$ with reaction rate $k_1$ ...
10
votes
6answers
812 views

Integrate gives wrong results

Integrate[a/(Sin[t]^2 + a^2), {t, 0, 2 Pi}] $$\int_0^{2 \pi } \frac{a}{a^2+\sin ^2(t)} \, dt$$ gives $0$ This cannot be true. What is going on? If I insert a ...
3
votes
0answers
38 views

Cross referencing symbols in different packages [duplicate]

I have problems with name space shadowing which I do not know how to resolve. I have two packages which depend on each other. Here is example of two files fooPackage.m: ...
1
vote
0answers
66 views

creation a table from a default module [closed]

I have used of bisection method for finding the root of a function: ...
4
votes
2answers
133 views

Imaginary terms in the derivative of Jacobi theta function (2) on the real line

I am trying to calculate/plot the derivative of the second Jacobi theta function $d\theta_2(0, e^{-\pi t} )/dt$. Calculating or plotting the function itself works fine: ...
11
votes
1answer
104 views

Is there a way to change the indentation behavior of the postfix operator //?

For example, using newlines after // results in some really weird indentation: Ideally, I'd love to be able to do something like this: ...
3
votes
1answer
81 views

Bilateral ZTransform

Is there support for bilateral Z-transform in Mathematica, or a third-party package?
4
votes
3answers
203 views

Replace values in a list based on conditions

I have a list with negative and positive numbers list = {-1, -2, 1, 2} and I want to replace all negative values with 0 and all positive values with 1 ...
7
votes
5answers
267 views

How to write an operator that acts on pure function (to give another pure function)

I would like to write an operator oper that acts on a pure function f with an undetermined number of arguments, with the syntax ...
3
votes
2answers
81 views

An conditional Sum of elements in Array [duplicate]

Consider we have: list = {{2, 3}, {3, 30}, {3, 2}, {4, 53}} and we want to compare the first elements and sum the second elements if first elements are similar ...
9
votes
0answers
149 views

Wrapping text around pasted graphic

I would like to use Mathematica to create all my documents for my high school math class. I cannot, however, find a way to copy and paste a diagram (let's say from Geogebra) and then place it where I ...
1
vote
1answer
50 views

Expand the plotting range [closed]

When use the following command to plot a graph Plot[x^(1/3), {x, -1, 1}] Mathematica does not show the range [0, 1]. It ...
3
votes
2answers
146 views

DiscretizeRegion of ImplicitRegion too small

I have a 2D function that has some sharp peeks within the my domain. I need to find a tight region that contains these sharp peeks. The following is an example of what I would like to do. An example ...
2
votes
1answer
97 views

Expand a product of operators

Lets suppose I have a family of operators $f_i$, and unknown c-numbers $a,b,c$. I want to expand such products: $(f_1+f_2+c)(f_3+f_2+b)$ into $b c+b f_2+b f_1+c f_2+c f_3+f_2^2+f_1 f_2+f_2 f_3+f_1 ...
1
vote
0answers
50 views

How to test for a non--zero rational function? [duplicate]

I want to test if a rational function in one variable is identically zero. I was surprised that just writing f==0 doesn't do it. I wrote the following code: ...
2
votes
2answers
335 views

Writing a function that returns a (usable) function

I am trying to create a function that returns Arnold's Cat Map of size n iterated k times. I can get something out of the Function command, but I can't figure out ...
2
votes
2answers
65 views

How can I pass values to a NamedSlot in TemplateApply

str="``;`v`;`v`;``"; template=StringTemplate@str; TemplateApply[template,CharacterRange["A","Z"]] (*"A;;;D"*) I want to get the result as: ...
2
votes
2answers
252 views

Having trouble translating Matlab `fsolve` into Mathematica

I searched the site and found that someone said FindRoot is equivalent to fsolve, however, without proper options, ...
31
votes
3answers
897 views

A better “VisibleSpectrum” function?

Since ColorData["VisibleSpectrum"] is wrong, I would like to have a more accurate function to use. Can this information be extracted from Mathematica itself?
19
votes
1answer
426 views

Faster binary Hamming weight for big integers?

While working on an answer to Count the sequences in an array I found that DigitCount was the bottleneck in my code when used as ...

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