# All Questions

312 views

### using index notation for finite differences

I am interested in deriving finite difference equations, which means I have to play around with indexed quantities. For example, for a 2D function f(x,y), I could discretize it on a grid with grid ...
142 views

### Problems with formatting a bar chart

I am trying to create a financial dashboard using Mathematica. I am having trouble formatting the axes ticks to show whole numbers. Further, when I hover over one of the chart elements, it is ...
283 views

### No Speedup Compiled Function in FindMinimum

The problem: I would like to minimize an objective function with respect to 12 variables. Minimization should be executed as fast as possible. Compiling the objective function increases the execution ...
142 views

### Texture[] not working properly with Image AlphaChannel

I recently encountered a problem when combining multiple texture layers in an graphics object when the texture comes from an image with alpha channel. Apparently the alpha channel of the image passed ...
36 views

### Pattern matching list elements in pure functions [duplicate]

Pattern matching here is a functional programming term, but it might be called differently in Mathematica, I'm not sure. It is possible to match the elements of the list in a regular function ...
209 views

### Plot lines keep disappearing

I'm trying to plot the Compton Shift which I've defined as: E2[ϕ_] := E1/(1 + (E1/(m*c^2))*(1 - Cos[ϕ Degree])) I've initiated the constants and when I evaluate ...
267 views

### How to compute MIN$(A(x), B(x))$

I have two polynomials: $\;A(x) = \sum a_i\;x^i$, $\quad B(x) = \sum b_i\;x^i$. Given $A(x)$, $B(x)$, I want to compute $\;C(x) =$MIN$(A(x), B(x)) = c_i\;x^i$ where $c_i =$MIN$(a_i, b_i)$. How can ...
540 views

### NIntegrate receiving a function with NumericQ which returns a list

Can some one please explain why ...
189 views

### Connection between Mathematica Connector/J and XAMPP MySQL Database

I have been fiddling around with a problem for a while now, and hope you can help me. Have searched for previous solutions, but nothing seems to work. My problem is as follows: I have XAMPP ...
328 views

### Refer to next element of list when iterating using Map [duplicate]

Is it possible to refer to the next element of the list when I'm using Map or should I always use For in this case? For example ...
515 views

### FindMinimum [] methods [closed]

Which algorithm is used when we do not use the option Method of FindMinimum[] function. FindMinimum[f,{x,x0}]
107 views

### ContourPlot of implicit function doesn't work when I square the equation [duplicate]

When I try this ...
336 views

### Is everything in Mathematica ultimately stored as a rule?

My current understanding about Mathematica is that everything, at the lowest level, ends up as replacement rules. First question: is this true? Second question: does Mathematica "gloss over" these ...
153 views

### What's wrong with my palindrome finding function?

I'm trying to find the palindromes in the dictionary, but my output isn't giving me all of them. I have this so far ...
28 views

### DialogInput inside ButtonBar freezes Mathematica [duplicate]

In Mathematica 8, if I press a button on a ButtonBar which contains a DialogInput Mathematica freezes. Is this reproducible and ...
602 views

### Differential equations: Solving a singular/nonlinear ODE using NDSolve

I am trying to numerically solve a rather horrible looking singular/nonlinear ode: A*(y''[x]/y[x])'' +y[x]^2==1 on the interval ...
110 views

### calling a batch or executable application on Windows

How to run a batch file, send commands and collects output on windows Run["!C:\\runme.bat"] it outputs 1 and a window appears and then disappears. I also want ...
266 views

How do I call AxesStyle->Arrowheads[ ] in order to control whether or not an arrow appears on each of the four ends of the axes in a ...
93 views

### File output and race conditions

Is it possible to know when Mathematica is done writing a file? I'm looking to automate something and I'm wanting to have Mathematica put it in a file using Put[], ...
202 views

### How to replace data in a list (tree) in a functional Mathematica way?

I have list containing 2D points in various groupings, i.e. points, lists of points (figures), lists of lists of points (patterns) and finally a list of patterns. The list also contains other data, ...
353 views

### Convert expression to C-form and simplifying

I have an expression which is the sum of many terms of the form $$\frac{0.00000000274341}{(0.000363856+(0.611425+z)^2)^{3/2}}$$ My problem is that I need to include this long expression in a ...
184 views

### Random filling of L-length line with l-length segments

I have discrete L-length line filled randomly with 2-length segments so its cover line with gaps 0 or 1. So we can describe cover configuration as sequence of gaps such as {0,0,1,0,1}. How I can ...
160 views

### Strange Behavior when making Equal Listable in Pick

While trying to make this problem more efficient I tried different methods and dabbled with making Greater and Equal ...
821 views

### How to increase Spectrogram resolution?

I have a time-domain signal that I want do a time-frequency analysis on it. When I tried the Spectrogram, I always get very low resolution. For example: I have a ...
362 views

### How to use NIntegrate in a purely numerical mode?

I have a function that is defined as the smallest root of a given polynomial. Something like this: ...
230 views

In the J/Link User Guide there is no example on how to use java.lang.Thread, from inside Mathematica. I'd like to know if is possible to start a thread from a ...
102 views

### Why only up to two \[Prime] superscripts are interpreted as derivatives?

I noticed that only up to two \[Prime] superscripts are interpreted as derivatives. Is there a reason for this restriction? Is it documented? ...
188 views

### Adding and summing overlapping Airy (or Gaussian) disks on a plane

In a previous question of mine, I asked how one might draw an Airy disk on a plane: Generating an Airy disk on a plane, and recieved some impressive answers from the users Timothy Wofford and ...
133 views

### What is the signature for a callback function for FinancialIndicators?

I'd like to write my own indicators to use with functions like TradingChart. From the context, it's clear that one needs to write a function whose parameters ...
173 views

### Copying each object in a plot separately as an image

I would like to copy a plot from Mathematica as an image, into a PowerPoint slide. This plot has two curves. When I try to do the (naïve) usual "copy graphics" and paste, I find the full plot (along ...
150 views

### Put results in multiple columns for comparison

One thing I would like to do in many instances is arrange input/output in columns for comparison. I expect that I need to use Grid to do this, but have not been ...
305 views

### Where did I go wrong with my implementation of the trapezoidal rule?

One method for doing quadrature, called the trapezoidal rule, improves accuracy by connecting the points on the curve corresponding to the points of subdivision with line segments, forming trapezoidal ...
1k views

### Singularity / stiffness / precision errors with NDSolve

I have a relatively simple 2nd Order ODE problem I'm trying to solve numerically $p'' + \frac{1}{r}p' = A(\frac{p(r)}{p(r) + k_{m}})$ where $A = 7.5795*10^9$ and $k_{m} = 1$. So trying to get ...
164 views

### Extract urls from list

If I have a list like list = {"my element 1 http://link.com", "http://link2.com my element 2"} how do I get a list of the links inside each element? Something ...
40 views

### How can I access numerical values of variables calculated with Solve? [duplicate]

I am trying to calculate some thermodynamical cycles so I often use lists with equations. Here's a simple example: ...
385 views

### fit a curve in a three dimensional space

I have a list of points of a curve in a three dimensional space, like ...
109 views

### Manually accept elements of a list

Let's say I have a list like: {"good element 1", "bad element 1", "good element 2", "good element 3", "bad element 2", ...} I would like to build a function that ...
125 views

### Defining a function of a distribution

I have a discrete- time and space markov process that I want to evolve given an initial distribution. To that, I defined ...
45 views

### How to manipulate lists to get only part of the value [duplicate]

This is really a question about manipulating the output of Maximize. I have a function of 2 variables, defined thus: ...
140 views

### Finding specific compositions of an Integer

I need to find all compositions of an integer L wherein all parts do not exсeed l and parts less then l cound not be neighbor. Here is my code ...
91 views

I'm using "mathlink.h" to call Mathematica from a C program. I send a computation to Mathematica and its return result is a very big number (100 digits). Hence, I want to read that number as a string. ...
751 views

### Plot3D with a log scale only along the y-axis

I would like to ask how to make a 3D plot (maybe using Plot3D) with a logarithmic scale along the y-axis? For example: I have a function, $f(x) = 2(1 + a\,x^4)/x^2$, where $x$ varies from 0 to 20 ...
234 views

### How do I find the most populous cities in the world?

I am attempting to plot the most populous cities on a world map. Currently, I have the line of code: ...
140 views

### Getting increased accuracy for roots of determinant

I have a matrix $a(\kappa)$ from which I am trying to determine $\kappa$ by using the equation $det(a(\kappa)) = 0$. The matrices I deal with are on the order of 100 X 100 to 500 X 500. Originally I ...
133 views

### Random number generation from a given distribution [duplicate]

Is there any way to obtain random numbers from a user defined continuous distribution in Mathematica? Thank you very much
204 views

### Setting up and solving system of equations

Consider the following code: ...
262 views

### How to improve gesture detection by JLink for the LeapMotion controller

Building on this thread (where I cannot add anything anymore somehow) and with this nice answer I kind of got swipe detection to work, but it is not very responsive. How to improve (in the sense of ...
171 views

### Remove overlapping red and green color

How to remove overlapping red and green color regions, leaving only red ones?