# All Questions

181 views

### Scalar product of two vectors have the least value

In geometry 3D, let $A(1,2,-3)$ and $B(-1,4,1)$ are two points. In the plane $(P):2x-3y+3z-17=0$, find a point $M$ such that the scalar product of two vectors $AM$ and $BM$ will have the least value. ...
232 views

### How to convert String to an Expression inside Manipulate which depends on control variable

Normally, in Global context, these 2 are equivalent eqn = "r-x"; r = -2; Plot[ToExpression[eqn], {x, -5, 5}] and ...
264 views

### How to pick out the element in a list of lists which satisfies a particular condition?

I have got a list: ...
294 views

### Elementwise, compilable min function

I am trying to implement efficiently a transfer-matrix like algorithm. On each iteration, I have two vectors $x=\{x_1,\dots,x_n\}$, $y=\{y_1,\dots,y_n\}$ with real numbers and I need to compute the ...
425 views

### How to solve simultaneous equations faster with Compile?

I have large 6x6 matrix Uwhich is a multiplication of 15 rotational matrix. All of the elements are Sin\[theta] and ...
201 views

### Control variable and body variable decoupling in Manipulate

This issue was raised as an offside problem in this thread. Consider the following example, that does not work as expected: ...
178 views

### Sum of roots of a trigonometric equation

The equation $$\sin x + \sqrt{3} \cos x = 1,$$ where $x \in [-2\pi, 2\pi]$ has four roots $-\dfrac{3\pi}{2}$, $\dfrac{\pi}{2}$, $\dfrac{\pi}{2}$ and $\dfrac{11\pi}{6}$. Sum of roots of the given ...
564 views

### Dynamically choosing which Manipulate controls to use

I have some stuff I would like to manipulate, using two different kinds of control, one at a time, using another variable as a switch. These controls are similar in principle to ...
622 views

### Place graph vertex labels in circles

Consider the following code: ...
243 views

### Determine page count programmatically [duplicate]

Possible Duplicate: Generating a table of contents By selecting File > Printing Settings > Headers and Footers from the menu, I am able to enter << Total Pages >> to print the total ...
614 views

### Is my expression too complicated for FullSimplify or am I doing something wrong?

I have a messily defined function $v(h, w)$ with $h, w \in \mathbb{R}$ and with a removable singularity at $h=1/2$, and I am trying to prove some of its properties using Mathematica. In particular I ...
700 views

### How can I get Mathematica to allow me to apply FindRoot to an expression that contains NIntegrate?

I am trying to run the following command in Mathematica: FindRoot[NIntegrate[D[f[x], x] / Sqrt[1 - x^2], {x, 0, 1}] - d, {a, 245}] As you might expect, a is ...
708 views

### How do I efficiently navigate the command line interface to Mathematica?

I would like to perfom such feats as cycling through previous commands, editing commands in place, etc. My expectation would be a readline-like interface, but this appears to not be the default.
866 views

I would like to expand a function $f(r)$ in the domain $[0,R]$, around the points $r =0$, and $r = R$ in the following manner $f(r = 0) = \Sigma_{i=0,i = even}^{imax} f_i (r/R)^i$ and $f(r = R) = ... 3answers 362 views ### equation solving problems I have some equation: $$veq=-2-lr-l^2r+2(r+ir^3\omega) v' + (-2+r)r^2v'^2 + (-2+r) r^2 v''==0$$ or in Mathematica form: ... 4answers 542 views ### How do I introduce a new variable in a trigonometric equation? I have the trigonometric equation \begin{equation*} \sin^8 x + 2\cos^8 x -\dfrac{1}{2}\cos^2 2x + 4\sin^2 x= 0. \end{equation*} By putting$t = \cos 2x$, I have \begin{equation*} \dfrac{3}{16} t^4+ ... 2answers 170 views ### Constraining a random function This question is a follow-up from here. I have a function that generates a list of correlations between some random variables: ... 1answer 694 views ### Functional programming and Do loops I'm writing a Monte Carlo simulation. I'm using a Do loop to create the different simulations, iterating over different ... 2answers 421 views ### Reduce and Solve unable to solve equation I have the following equation. Why aren't Solve and Reduce able to find the solution? ... 1answer 705 views ### Solving a PDE containing DiracDelta I want to get the answer from a PDE:$\begin{align*} \frac{\partial \rho(r,t)}{\partial t}&=Dr^{-2}\frac{\partial}{\partial r}r^2h(r)e^{-U(r)}\frac{\partial}{\partial ... 1answer 2k views ### Nested If statements When I do this: Apply[(If[#2 == what, "yay", If[#2 == whoops, "nay"]]) &, {-5, what}] I get: yay But when I do this: ... 1answer 197 views ### Prevent interdependence of controls My question is probably best illustrated with this small sample code: ... 1answer 59 views ### What is the most elegant way to see if an expression is affected by a certain symbol? [duplicate] Possible Duplicate: Determine whether some expression contains a given symbol Let's say I have some expression: sample = {1, 1/q, f[m]} And I want to ... 3answers 1k views ### False Color SEM image with Mathematica I have a question regarding colouring and binary image filtering, but unfortunately, the system doesn't permit the inclusion of images for first-timers. If anyone would like to see the images ... 4answers 569 views ### How can a big table be treated as a database? I often work with big tables that I want to treat kind of like a database. Here's an example table. ... 1answer 263 views ### Is it possible to Clear all variables (but not functions)? I have written a Mathematica script in which I define functions and variables. Here is a vastly simplified example: ... 2answers 1k views ### How to quickly calculate intersections of filled curves? I am trying to quickly calculate the intersection of polygons with more than 6,000 points. A compiled solution would be preferable. Here is one example of the problem: ... 0answers 119 views ### Package for voting systems Is there a mathematica package that implements common voting systems (like IRV where voters will rank the candidates)? 2answers 325 views ### Rules governing Plot line generation I was looking at the Documentation Center for Round, Ceiling and Floor when I noticed that ... 3answers 889 views ### Determine if solution to linear system exists I'm trying to determine only if a solution to a linear system of equations exists. I have been using LinearSolve, which works fine, but it solves the system as ... 0answers 210 views ### Accessing MathematicaScript over ssh/network Here is the conundrum I am faced with. I have two computer. One with Mathematica (and hence MathematicaScript) but generally poor resources. The other without ... 1answer 232 views ### Timing differences between multiple executions of identical code I have a list of pairs of numbers and I'd like to change the sign of the second element in each pair i.e.(a,b)\rightarrow (a,-b)\$. I'm sure there are many ...
112 views

This question on importing news headlines via a RSS feed reminded me of an old question I've been meaning to ask. Past attempts at finding a use for Mathematica's RSS to Notebook capabilities were ...
380 views

### Merging (combining) tables of graph relationships (2-mode to 1-mode network)

I have some data of corporate board members in Australia in excel format here (Dropbox public link). It is the data behind this graph. The first worksheet is of all the vertexes (directors and ...
173 views

### Change values in equation with slider

I want to make an equation where the values adjust to my slider which I inserted with manipulate. Well, I tried, but when I use the slider the equation starts to fall apart. Actually this should ...
697 views

### How to visualize the voting choices in the moderator elections?

I'm trying to use Mathematica to create some visual representations of the votes cast in the recent Mathematica-StackExchange moderator elections. (Not the vote-counting system itself, OpenSTV, but ...
182 views

### Unable to evaluate reasonable max expression

Consider the following statement: Max[0, Sqrt[1 - Cos[4 \[Theta]]]] You'll find that Mathematica won't evaluate this, because it doesn't know the range of ...
197 views

### Layout a second graph of the same nodes in the same way

I have a number of graphs with the same nodes. I would like to be able to somehow save the layout that results from the spring embedded results of one graph (the first image), and have the other ...
251 views

### Plotting a floor function with endpoints?

Would someone mind showing me how to plot a floor function with the appropriate endpoints? I tried Google, but the best I could find was something posted from 2004 that no longer appears to work. ...
159 views

### How to add FindDivisions to the plot commands?

I used these instructions to make a legend bar next to my plot (I can't comment there) But I'm lost to where and how can I add FindDivisions to the DensityPlot under "Edit: illustrating additional ...
342 views

### Control parameters of different styles of DistributionChart

Using DistributionChart, you can choose among several styles aka ChartElementFunction: ...
380 views

### Exporting to quicktime in linux version?

In MMA (8.0.0/Linux), I tried to to create an animation using the command Export["s4s5mov.mov", listOfFigures] and got the output Doing a little research, one ...
2k views

### Convert a string to hex number?

How can I convert a string containing a hex number such as "6b" to a hex digit that mathematica can use to do math with? I have tried using ...
462 views

### Solving Differential Equation depending on variables solved by NDSolve

How to solve a differential equation which consists of variables depending upon another differential equation?
136 views

### Using MaxStepFraction as ticks on plot

Is there any way I could use the MaxStepFraction (or grid size) as used in NDSolve in the example below as ticks on the 3d Plot? ...
315 views

### How to get dynamic results of the values in three InputFields

I have three InputField-s which have no initial value. I would like all InputFields to have a value in descending order and for ...
1k views

### Creating a random normal matrix

I would like to create a random matrix with the constraint that the matrix must be normal, i.e. the matrix and its Hermitian conjugate must commute. I would create a random matrix "without ...
451 views

### Toggle visibility of elements in a plot

I have three simple graphs in one Plot. Now I am trying to make a button for each graph so you can hide or show it in the plot. Until now I was just able to make a checkbox with the Manipulate ...