# All Questions

940 views

### Difference between @ and @@

I am confused by the commands @ and @@. From the documentation, I learnt that @@ is the ...
51 views

### Quit Kernel Shortcut [duplicate]

How could I set a Keyboard shortcut for the Quit Kernel -> Local command? I find really disappointing to open the Evaluation menu any time!
248 views

### Linear Stability Analysis Routine. Normal Modes in NDSolve

I want to make the linear stability analyis of a nonlinear system of PDEs. So for example then I want to plot what happens to the amplitudes of the modes. To do that I need to solve my equations with ...
408 views

### Solving recurrence relationship using iteration

I am trying to create a Mathematica function that basically splits up a continuous function (in this case a physical potential) into steps (strips as it were) and returns the value of the function at ...
479 views

### FindMinimum produces error message

I'm trying to solve a logistic regression problem using Mathematica -- more to improve my Mathematica skills than to solve the problem as I have already solved it using Octave. The problem I am ...
547 views

### How to visualize the interior of a complicated 3d plot

I have an external data file (can be downloaded here: link 1 or link 2) which contains a dense grid of initial condition in the (x,y,z) space. I read it with Mathematica and plot these initial ...
144 views

### Add a letter to a variable name from a list

Basically I am searching for a way to add the letter u to an existing list of variables {a,b,c,d} to obtain the variable list ...
442 views

### Plotting a Gravity-Field [duplicate]

I try to plot a 2D gravity field or something similar in the form like $r/|r|^3$ with the standart builtin VectorPlot function: ...
233 views

### Dimension of an algebraic variety

I would like to compute, using Groebner bases, the dimension of the variety defined by a set of polynomials in several variables. In the wikipedia page the method is described, and an implementation ...
126 views

### Positioning Labeled points in ListPlot gives unexpected results and errors

Original question can be seen in the edit history.... UPDATE: a simpler example - same "problem" ...
141 views

### A function that (also) changes a replacement rule

I'd like to write a function operating on a list, returning a list, but also changing a replacement rule. Let's say I have a list of replacement rules: ...
395 views

### Von Mangoldt function

Can anybody evaluate the following sum for me $$\sum\limits_{n=2}^\infty(-1)^n\left(\frac{\psi(n)}{n}-\frac{\Lambda(n)}{2n}\right)$$ where $\psi(n)$ is the Chebyshev function and $\Lambda(n)$ is ...
148 views

### Fourier-Analysis How to display every period correctly? [duplicate]

I want to express a function as a sum of fourier series. I tried the code below. It works. But only get one period (from 0 to 1). How to display every period correctly? ...
117 views

### Showing the value a plotted function achieves at the right-most point of the plot domain

I'm plotting results from NDSolve, and I'd like to clip them with their value at the point where the line is clipped. So where the curve ends at the edge of the plot, there would be a number ...
456 views

### FindRoot giving false roots with Bessel Functions

I have read in some places about the errors associated with FindRoot, but the closest thing I can find on this website seems to be due to the imaginary unit. I am dealing with what should be a ...
354 views

### Code to give center of circle given three points in 2D? [duplicate]

does anyone know how to make a function C(p1,p2,p3)=center of circle that goes through p1, p2, and p3? This is in 2D Sorry this is poorly written but I ...
175 views

### Are there built-in functions for testing if a point lies within Graphics3D primitives?

I noticed in this question, Behavior of GraphicsMeshInPolygonQ with self-intersecting polygons, that Mathematica has some "psuedo-hidden" functionality for allowing one to quickly perform a winding ...
130 views

### Drawing a large set of Graphics3D cylinders provided a set of cylinder specifications in a list

I'd like to draw a large number of 3D cylinders using Graphics3D. My list specifying the cylinders has elements that look like the following: ...
82 views

### How can I influence the elements plotted in a BubbleChart depending on the tuple plotted?

In a BubbleChart, how can influence the elements plotted depending on a value in the tuple plotted? I want to create a BubbleChart from the following data: ...
198 views

### Run FileSystem Remotely and Front End/Kernel Locally

Is there a way to run both the front end(& kernel) locally while the having Mathematica's filesystem(inode's at minimum) reference another os's filesystem? For example currently I run ...
88 views

### Collecting variables from Subscript

I have followings set: t = Transpose[{x[#] & /@ Range[20], RandomInteger[15, 20]}]; Subscript[#[[1]], #[[2]]] & /@ t The code is just to build my set.So ...
126 views

### Make the y-axis of a plot be in terms of an arbitrary parameter instead of a number?

Sorry if the title is wordy. Basically what I am asking would probably be easier if I just use an example. Say I wanted to plot f(x) = Asin(x) and have the graph come up with the sine function, and ...
207 views

### Opacity and overlapping points on ListPlot3D

I am plotting a dataset on ListPointPlot3D, and in order to give an idea of density of points I used opacity of 0.5. The problem is that that while the opacity of points behind one another is added, ...
636 views

### How to calculate the $H_2$ and $H_\infty$ norms of TransferFunctionModels or StateSpaceModels?

Lets assume we have a system model: ...
2k views

### Paths integrals in the complex plane

I can't find how to calculate path integrals of complex functions in the complex plane. For example: $$\oint_{\mid z \mid =2}\frac{1-e^z+z}{z^3 (z-1)^2}dz$$
84 views

### How to close all other MathKernel before opening the new one?

I use MathLink to call Mathematica from C program. After any opening to Mathematica, I do close the connection. However, I don't know why some connections are ...
123 views

### Definite Integral. Perfomance problem

I have a notebook in Mathematica 4. I'm trying to convert it to use in Mathematica 9. One of the problem is the long computation of definite integral. In Mathematica 4 the result of the following code ...
194 views

### Symbol with Subscript but no quotes in it!

If I use the following function to define me a fancy subscript: ...
226 views

### Manipulating List

I have a list: b={{1, 1}, {2, 2}, {3, 3}, {5, 5}, {6, 6}, {8, 8}, {10, 10}} I want to insert the elements in this list: ...
744 views

### How to rotate the z label in 3D plots

Let's take the following simple and funny case ...
113 views

### Amount of k-sized not-duplicated subsets of subsets of pair with disitinct sorted integers

I have a list, L, of this kind ($n\in \mathbb{N}$): L=Sort[RandomSample[Subsets[Range[n],{2}],RandomInteger[{1,Binomial[n,2]}]]] S contains any k-sized subset ...
246 views

### How to simplify an expression with square roots?

The expression $\sqrt{L^2 M+\sqrt{L^2 (-J^2 + L^2 M^2)}}/\sqrt{2}$，can be simplified into $\sqrt{L}(\sqrt{LM + J}+\sqrt{LM - J})/2$, but how can I obtain this result with Mathematica? That is, how ...
156 views

### Get the first positive coefficient in polynomial?

I have Polynomial $F(x) = \sum_{i \leq n}{a_ix^i}$. How to get the first $a_i > 0$? Thanks,
72 views

### The number of real values assumed by combinations of complex roots of a decic

Define complex conjugate as the pair of complex numbers $a+bi,a-bi$. Assume you have 5 such pairs and they are the 10 roots $x_i$ of a 10th-deg equation with integer coefficients. In general, how many ...
269 views

### How to programmatically remove menu items

I would like to do the opposite of what is described here. So rather than add a menu item I would like to programmatically remove one (or more). So given a knowledge of the structure of the menu *.tr ...
168 views

### What's wrong with my graph input?

So I saw this picture on my book and it was left as an exercise to figure out. This is what I have so far, but I'm not sure where I went wrong. ...
43 views

### Generate effective C/Java code (minimizing operations) [duplicate]

Is it possible to generate C/Java code with Mathematica so that it minimizes number of operations performed? For example, for matrix inverse or determinant? With good caching variables?
74 views

### Details of automatic cell-grouping w.r.t. cell-style

What determines how a specific cell-style influences grouping of cells? For example "Text" following "Subtitle" is grouped but ...
942 views

### combining and comparing lists

I have 2 lists (of lists), where most of the contained lists match. That is, the lists contained in list1 mostly match the lists contained in list2. In this simplified example each of the inner ...
319 views

### Using NSolve in the complex plane

I am trying to find numerical values for $\Im\ e^{\frac{1}{2} +i\ y} = \Im\ \zeta(\frac{1}{2} +i\ y)$ for a given range. I have tried: ...
350 views

### Calculate scalar potential from electric field

Is it possible for Mathematica to solve an equation like $\nabla f(\mathbf{r}) = - \mathbf{E}(\mathbf{r})$ for $f(\mathbf{r})$? I tried ...
1k views

### Best way to compute row eigenvectors

Without qualification, the term eigenvectors (of a matrix) refers to the column eigenvectors (of a matrix) and can be directly computed with Eigenvectors[]. To get ...
548 views

### Table of Variables

I use a list of variables {x1, x2, x3} to Solve a particular set of equations. I am now trying to generalise this depending on ...
324 views

### Colors for multiple piecewise functions

I have the following $3$ piecewise functions, and I would like that f1, f2 and f3 have $3$ ...
205 views

### How to prevent axes label and tick labels from being placed inside a 3D plot

Consider the following toy-code: ...
120 views

### Caching data in Mathematica package

Consider the following: m=Quantity[1,"meter"] If I run the package, it will return 1m But when I load the package, the ...
198 views

### WhenEvent method with 3 conditions

I am trying to solve system of differential equations below $$x''(t)=-2.25cos(1.5t)-x(t)-x'(t)$$ $$y''(t)=-1.125cos(1.5t)-4y(t)-y'(t)$$ z'(t)=\begin{cases}x(t)-(1+y(t)), & \text{if } ...
387 views

### Partitioning a list of numbers the Mathematica way

I have two sorted lists, one list will be called the "fences" and the other the "values" Fences could be: $\{1, 5, 9, 14\}$ Values could be $\{-1, 1, 3, 4, 6, 9, 10, 13, 14, 15\}$ I want to ...