# All Questions

986 views

### ODE and BVP: NDSolve errors

The mathematical problem is shown here. I tried to solve writing the ...
769 views

### A matrix-vector cross product

I want to do a cross product involving a vector of Pauli matrices $\vec \sigma = \left( {{\sigma _1},{\sigma _2},{\sigma _3}} \right)$; for example, $\vec \sigma \times \left( {1,2,3} \right)$. ...
136 views

### Strange behavior of Integrate

I'm trying to calculate the following integral using Mathematica 9.0.1.0 a11=Integrate[Abs[Sin[b+x]],{x,0,2*\[Pi]}] This should be a simple problem; however, it ...
211 views

### Notebook UI: Autocompletion - Display function arguments when typing?

Is there a setting to display the required arguments of a function when typing as Visual Studio, Matlab, etc. does?
317 views

### In what situation is the use of Directive required?

Sometimes I see code samples in the document or in this site using Directive, but I haven't yet find a case that Directive is ...
117 views

### Expand List Operation

On applying a multiplication and subtraction on a list, like so: x = 2y - 4; Where y is a list containing fractions of complex numbers generated from dynamic ...
929 views

### How to plot and solve the numerical solution of a integro-differential equation

I have a integro-differential equation of the form $y'(t) = - \int_0^t {y(t_1 )} e^{t_1 - t} dt_1, {\rm{ t}} \in {\rm{[0,10], y(0) = 1}}$ My code is: ...
153 views

question1: (code 1 something wrong, Why? and how to overcome this to achieve the next code's effect) ...
81 views

### Replace expression using a tuple

Given an expression in x, y, z (for example), and a list with three elements, like ...
420 views

### FourierSeries for rational function looks wrong

I have the following code: ser[x_] = FourierSeries[(\[Pi]^2 + a)/(3 x^2 + a), x, 10] // N // Chop It gives me some series, which I then try to plot. And ...
389 views

### Checking if an expression is equal to zero

I have 6 points in $\mathbb R^3$ as follows: ...
147 views

### Rearranging a set of numbers

I have this set of numbers, that is a range of prices (ie 6-10) and a quantity of products (5) ...
578 views

### Calculate variance of random walk?

How can I symbolically calculate the variance of the following random walk in Mathematica? Given several discrete random variables such that $p(Z_i=1-2k)=p$, where $k$ is a small real number, and ...
135 views

### Cannot run Mathematica C-interfacing examples 'factor'

I am trying to run a Mathematica example concerning Mathematica interfacing issues with C programs. In particular I am trying to call a Mathematica function from C. Example ...
169 views

### How can I combine two Pick expressions into one?

I want to speed up my code, i.e., replace Select by Pick. I think using two Pick ...
1k views

### Compiling more functions that don't call MainEvaluate

I would like to use Compile with functions defined outside Compile. For example if I have the two basic functions F and G F[x_] := x + 2 G[x_] := x And I want ...
466 views

### What does the Error Message in DSolve really mean?

Having this ordinary non linear differential equation $$y'-x^2 (y+1)\cdot (y+2)^2= 0$$ with the boundary condition $y(4)=2$. When trying to solve this one with Mathematica by using ...
278 views

### how to reduce the time to calculate triple integral

i want to evaluate the following integral, but it takes 15 min to do it. i must reduce the time to calculate it, i have to do a table and create a graph, but takes too long. anyone have an idea ? ...
732 views

### Plotting heat equation in a Manipulate expression

I have a 2D heat equation $u_t = \alpha (u_{xx} + u_{yy})$ with conditions: $u(x, y, 0) = 300$, $u_y(x, 0, t) = \mu_1(x)$, $u_y(x, 1, t) = \mu_2(x)$, $u(0, y, t) = \mu_3(y)$, \$u(1, y, t) = ...
158 views

### How to dynamically change the Appearance of a control in Manipulate?

How can I dynamically change the appearance of b? Strangely it works for the Enabled state but not for the Appearance. Thanks. ...
321 views

### Create a table with inline conditions

I am trying to create a table with conditionals inline. For example, I'd like to create a 2 dimensional table like this: ...
221 views

### FindFit: Fit that is always lower - Change of Norm?

I am trying to find a fitting function for a multidimensional set of data. I will have to find a fitting function that is always lower (conservative) than the data fitted. The easiest way is to look ...
62 views

### Don't pollute outside context when solving equation from the outside

This code works fine only if a is not defined in the outside context: ...
279 views

### webMathematica interface for Mobile apps

I was reading about webmathematica but it has mentioned that it is for websites and mobile apps depend on wolfram alpha to get its work done. But since exact mathematica code doesn't work in alpha, it ...
318 views

### How to populate a table using a rule replacement

I am trying to populate the rows and columns of a table by using a rule replacment. To generate a table that looks like this For example Sc would be row 1, column 1. An example of a record looks ...
138 views

### How to track dynamically generated manipulators?

In the code below the manipulators that are generated from the stakes buttons are not tracked by the Manipulate expression that contains them. How can I make the ...
140 views

### Minimize failing on a polynomial

Calling: Minimize[{-0.4877 - 0.1190 r^2 - 0.1885 r^4 + 2.9703 z - 0.5531 z^2, 0 <= z <= 3.5 ∧ 0 <= r <= 1.75}, {r, z}] returns ...
140 views

### direct assignment to the element in a Table

I have already asked a related question here why set values in this way doesn't work? But I think I have to write the question which I encountered explicitly? ...
2k views

### Open-source IntelliJIDEA plugin to support Mathematica development

Although we already had a question asking for development alternatives to Wolfram Workbench, I want to ask a more specific question: One of the most advanced IDE's especially for Java programming ...
712 views

### How can I conveniently call igraph through RLink?

Mathematica has lots of functions for working with graphs, but this functionality is not yet as mature as the igraph library. It is useful to have access to igraph from Mathematica, both for ...
644 views

### Mathematica equivalent of regex '\w{2,3}'

It beats me to write the Mathematica pattern equivalent to the regex: \w{2,3} Any ideas?
308 views

### How to normalize parts of matrix elements?

To normalize the last 2 or more columns of a matrix, ...
318 views

### DownValue “associative array” to list? [duplicate]

I have a "sparse array" like this arr[1.5]=0.4, arr[3.5]=0.7, arr[7]=0.3 which is not really a sparse array since the keys are not all integers. This is like a ...
103 views

### Help generating dynamic manipulators?

I would like to generate dynamic Manipulators for each of the selected buttons in a ToggleBar. How can I keep the state of each Manipulator in a variable? I would like to later access the values of ...
440 views

### Manipulate slider unresponsive after suspend in Linux

I've tested Linux Mathematica versions 7-9 on various Linux distributions, with identical problem: after suspend/resume cycle my Manipulate controls (i.e. sliders&buttons) appear unresponsive, ...
456 views

### CoordinateTransform from Cartesian to Spherical

I have a set of coordinates on the sphere in terms of cartesian coordinates. I would like to convert them to spherical data points. However, when I try to convert the point {0, 0, 1} it tells me that ...
55 views

### Problem using replace to simplify logarithms [duplicate]

Is there a way to combine logarithm terms like 9 m Log[m]-9 m Log[M]+16 m M Log[m]-16 m M Log[M] into ...
426 views

### How to insert a zoom inside the main plot

As the title indicates, I want to add inside the main plot (preferably at the lower left part) a zoom. Here is the corresponding Mathematica code: ...
321 views

### Exporting PDF file - incorrect graphic [closed]

I export graphics to PDF using: Export["/path/figure.pdf", plotname] It gives me more than enough quality for PDFLatex. But somehow, some exported plots have ...
257 views

### Is mathematica storing information it shouldn't store?

I'm seeking to find solutions to a numerical integration with a large set of parameter combinations (basically, I'm doing a brute parameter sampling). Yet, I believe the memory of the computer is ...
337 views

### Join all square root expressions?

Sometimes I observe Mathematica produce expressions exactly like the following after a simplification step: $$\frac{a+\sqrt{-(1-b)}\sqrt{\frac{1}{b-1}}}{\sqrt{c}\sqrt{\frac{1}{c}}}$$ Now, any ...
381 views

### Solve equations real and imaginary part separately

For my system of equations, the procedure described in Solving complex equations of using Reduce works no more. How can I separate the real and imaginary part of ...
355 views

### Generating a “flare” effect in Graphics3D?

I'm attempting to indicate that there is a point-source of light at some position in a Graphics3D-generated image. Is there any built-in tool to do this? My patch-work solution thus far has been to ...
88 views

### How can I find ,Which InputField was recently updated?

I have 4 InputFields.I want to find which InputField was recently Updated out of all ...
245 views

### How to set the slider width inside Manipulate

I use the code below to visualise the connection between a sine curve and the unit circle, but would like to make the slider wider, so it has at least almost the same with as the image. I have tried ...
797 views

### Instruct a Table to only evaluate until a condition is fulfilled

I am looking for the way of building a Table of pairs of numbers in a fast way. My true table evaluates huge functions, and I see no way and reason to show those cumbersome expressions here. Let us ...
186 views

### why set values in this way doesn't work?

question is as follows define a list ttt={1,2}; and if I set values in this way {ttt[[1]],ttt[[2]]}={3,4} then the value ...
178 views

### Predictive code completion and custom functions in contexts

Suppose I work for organisation PQR, and have been developing a suite of packages, PQRUtilities, PQRVisualization etc, all of ...