0
votes
2answers
471 views

Is it possible to use WolframAlpha servers to evaluate equations in Mathematica v8.0.4?

Is it possible to use WolframAlpha computational power to evaluate equations in Mathematica version 8.0.4? The thing is, it takes ages for my computer to evaluate certain equations. It would be ...
10
votes
2answers
465 views

Dynamic graphics are less responsive inside a Manipulate

I have some code which displays a GraphPlot and allows the user to click on any vertex in the graph to display some information about that vertex in a popup window. ...
5
votes
4answers
262 views

Manipulate flickering and consuming lots of CPU

I am new to Mathematica and was experimenting with a simply problem of plotting a tangent to a curve and being able to move the point at which the tangent is drawn using ...
3
votes
3answers
231 views

How to transform and swap columns of this matrix in a simple way? Version 2

So, earlier today I asked the question How to transform this matrix & swap its columns in a simple way? and was given useful and elaborated answers. Now, I'm still not used to the "Array", ...
0
votes
2answers
554 views

How to get complement from two matrices?

This is a special case of my question How to do nor on matrices? ...
3
votes
4answers
338 views

How to transform this matrix & swap its columns in a simple way?

I would like to transform matrix $\mathbf A = \begin{pmatrix} a&b&i&j\\ c&d&k&l \\ e&f&m&n \\ g&h&o&p \end{pmatrix}$ into matrix $\mathbf B = ...
3
votes
1answer
153 views

How to make a simple tree yourself with defined distances for each generation?

I'm trying to make a function that generates a tree for spin spin analysis in spectroscopy. I though it would be pretty easy, but I'm totally stocked. The tree should look something like this: ...
0
votes
1answer
152 views

How to do nor on matrices?

Supose I have matrices a b and c like a = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}; b = {7, 8, 9}; c = {{1},{4},{7}}; I want to get ...
5
votes
2answers
419 views

How to declare a function of variable?

In my program, there are many functions relying on spatial coordinates: x, y, and z, which are also functions of time t, i.e., composite function. I need to differentiate some functions for example f: ...
3
votes
1answer
143 views

Creation of name.m Package

I have a structure of folders. Main Directory( has init.m, and name.m files) Subfolders under Main directory library ( has the packages, pacakge1.m, package2.m) Data (some xcel sheets and other ...
0
votes
1answer
1k views

Complex line integral

Can someone recommend an online article or introductory tutorial that will show me how to do real and complex line integrals using Mathematica?
7
votes
2answers
646 views

How to change an expression to Fortran90 form?

I have a large expression produced by Mathematica. To use this expression in my Fortran program I need to change it to a Fortran90 form. I am not satisfied with the ...
0
votes
0answers
96 views

DensityPlot on spherical surface? [duplicate]

I just checked this example Construct a Globe Showing All Weather Stations. It looks good, but I would like to add a density plot of the stations on the spherical surface. This can be done with the ...
7
votes
2answers
130 views

Method that can be used to collect the variables of a function

Suppose we have a function f[x, y, z] and we want to get all its variables Sequence[x,y,z], what method can we use then? The ...
12
votes
2answers
580 views

Simplify assumes Boolean 1 and 0 in logical expressions

Per this chat discussion and this previous question where I encountered the strange behaviour: ...
9
votes
2answers
1k views

Badly conditioned matrix (General::luc)

With some matrices I am receiving the following message ...
4
votes
1answer
367 views

iterating piecewise linear maps on [0,1]

I have been trying to make code work for iterating piecewise linear maps on the unit interval in Mathematica to compare with MATLAB and Maple. Tent and logistic maps are easy to implement but ...
4
votes
1answer
362 views

NDSolve problem with matrix valued function

I got a strange problem when using NDSolve to solve a matrix value function σ[t] = {{σx[t], σxy[t]}, {σyx[t], σy[t]}} when I ...
8
votes
3answers
301 views

Patternmatching sets

How to match set-patterns against sets? A set (in the mathematical sense) is a list of elements without repetition and order of elements does not matter. For example, we have a pattern set ...
5
votes
1answer
194 views

Using CellPrint with a TraditionalForm string

I am trying to use CellPrint to print a cell that asks a user to solve an equation. This equation is randomly generated right beforehand, and I would like to have it print in Blue. The whole Cell ...
5
votes
2answers
431 views

Contour plot doesn't look right

I have an implicit function expression ...
0
votes
2answers
197 views

Number of edges to each polygon of a graph constructed from an image

I have an image which looks like from How to convert an image to a graph and get the positions of the edges? which by using MorphologicalGraph becomes a graph ...
0
votes
1answer
238 views

Why does my attempt at parallelization not work?

I want to run some function with different parameters, parallel on 4 cores (i5). When I run it without using Parallelize, processor has ~25% utilization. It's a ...
1
vote
0answers
189 views

Automatic inverse for Lambert’s Azimuthal Equal-Area Projection

I’m interested in finding closed-form inverses for map projection equations in general (of course, this is not always possible). I’m hoping Mathematica can help me with some of the trickier ones. As ...
3
votes
1answer
234 views

An ancient MIDI keyboard?

There is a demostration project http://demonstrations.wolfram.com/KeyboardAndComposer/ where you can compose Western music using a 97 keys simulated midi keyboard. I study eastern and ancient music ...
4
votes
2answers
222 views

Partition a set into $k$ non-empty subsets

The Stirling number of the second kind is the number of ways to partition a set of $n$ objects into $k$ non-empty subsets. In Mathematica, this is implemented as ...
110
votes
1answer
21k views

Mathematica Minecraft

Some time ago I asked myself: with all these great graphics and interactive capabilities of Mathematica, what kinds of 3D games can be implemented in it? And the answer which came to mind is ...
11
votes
1answer
245 views

Is it possible to use Compile on a function with optional arguments?

My Mathematica is a little rusty, so apologies in advance. I think my problem is quite simple, but I can't seem to find the answer on my own! Simple example : ...
8
votes
2answers
184 views

How do I write a function that can be used in a rule to modify both sides of an equation? [duplicate]

I sometimes need fine grain control over equations in Mathematica in order to help me understand how to solve a problem manually. A greatly simplified example of a session might be something like ...
6
votes
2answers
325 views

Distorted graphics when using custom ticks and AspectRatio -> Full

I am having a problem using custom tick specifications along with AspectRatio -> Full. The problem affects both Ticks and ...
1
vote
3answers
809 views

Finding the square root of a random number with Newton's method, using While/Do/For loops?

I am trying to construct a program that will find the square root of a number, using Newton's method, which is $$x(n+1) = x_n- f(x) / f'(x_n)$$ The number, will be a random number, generated by: ...
2
votes
0answers
106 views

Strange double evaluation using MorphologicalGraph

(MMA 9.0.0 on Mac OS/X 10.8) Please consider the following snippet (this is as SMALL as I could make it -- my attempts at making a smaller repro-case eliminated the effect that I am investigating) ...
1
vote
1answer
149 views

Efficient way to give symbolic elements symmetry

I have a symbolic expression that represents a set of operators. These operators have quite a bit of symmetry to simplify expressions: ...
16
votes
1answer
204 views

Exclude Sections/Subsections/… from evaluation

I'm working on a large notebook and I want to exclude some sections and subsections from being evaluated when I evaluate the whole notebook. Is there a way to exclude specific sections or ...
0
votes
1answer
317 views

NIntegrate Error-Estimate Question

When I do some complicated 4-dimensional integral numerically, Mathematica tells me its estimate for the value of the integral, and its estimate for the value of the error in the calculation. The ...
1
vote
2answers
815 views

How to make plot with frame and two different scales on the x-axis (CMB power spectrum example)

Let us take CMB spectrum as an example. I get data of $C_l$ as a function of multipole moment $l$. Also, multipole moment is a function of angular scale. The question is: how to make a plot with a ...
2
votes
3answers
867 views

Why doesn't Mathematica make an obvious simplification?

I am doing some calculation with summation and the Kronecker symbol. Here are my steps : ...
2
votes
2answers
1k views

Product of Fibonacci numbers using For/Do/While loops

I want to find the product of the first 20 Fibonacci numbers (the fibonorial). I want implementations using While, Do, and ...
7
votes
3answers
315 views

Piping and Replacement

I haven't been able to figure out how to use piping with certain functions. Specifically, I would like to apply a replacement at the end of a pipe, like the following: ...
2
votes
2answers
1k views

Faster way to convert real strings into numbers [duplicate]

Working with big files, I have to convert some numbers that are in string format into real MMA numbers. I know that I can use ToExpression but it's slow when ...
2
votes
1answer
213 views

Grid generation around airfoil from data

Here is the data http://wikisend.com/download/405620/datapoints.dat I have (x,y) data for a grid around an airfoil and I am trying to figure out how I can draw radial and polar lines for the grid to ...
3
votes
2answers
211 views

How can this DivisorSigma code be made fast?

Since Project Euler problems are now fair game for questions I have a question of my own. A certain problem* states: For a positive integer n, let σ2(n) be the sum of the squares of its ...
2
votes
1answer
434 views

Importing data sets from plain-text files and performing operations on them

I am working with a lot of daily weather files in the txt format. I need to calculate a daily quantity from each of them, e.g., daily light intensity, which ...
3
votes
3answers
515 views

Sum of Multinomial Coefficients

Basically, I want to write a function to compute the following sum $f(m,L):=\sum_{0\leq k_1,\cdots, k_n\leq m} \binom{m}{k_1,k_2,\cdots k_n}$ and $\mathrm{supp}(k)=L \subseteq \left \{ 1,...,n \right ...
3
votes
1answer
4k views

Quick Hessian matrix and gradient calculation?

I am absolutely new to Mathematica and I actually want to try implementing a little optimization method . Long story short assuming I have a predefined two-variable function f(x,y) I want to ...
6
votes
1answer
209 views

Obtaining standardised regression coeffiecients

Regression coefficients are the constant that indicate the rate of change in one variable as a function of change in another. Standardised regression coefficients are the same, but refer to a change ...
3
votes
2answers
130 views

Find condition under which variables fall away

I have a somewhat lengthy expression, looking like expr = 1 + x + b + Pi + 2*a Is there some way of generating a relationship between ...
-1
votes
1answer
294 views

Where is KeyEventTranslations.tr in Mathematica 9?

I can't find the file in it's usual place /Library/Mathematica/FrontEnd/... was it removed?
1
vote
2answers
602 views

Parametric plot from two NDsolve solutions

I have two independent ODE systems. A = NDsolve[..., {x, y}, {t, 0, 10}]; B = NDsolve[..., {a, b}, {t, 0, 10}]; I can draw a ...
6
votes
0answers
289 views

Reproducing the Integral Definition of the Modified Bessel function

I need to simplify some integral expressions in terms of special functions, such as the modified Bessel function of the first kind. See for example Eq. (5) on this page. Notice that the real ...

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