1
vote
1answer
115 views

Operator operation

There are two basic operators r={x,y,z} and p=-I*h*{D[#,x] , D[#,y], D[#,z]} &. The angular momentum operator is defined as ...
2
votes
0answers
57 views

Can BreadthFirstScan be modified?

I would like to obtain a "slick" implementation of A*-search algorithm on Graph objects, using the built-in BreadthFirstScan (if that is possible at all). I noticed that BreadthFirstScan is static in ...
3
votes
0answers
117 views

What can I do to improve the performance of my calculations?

I'm trying to express a simple probability problem in Mathematica, but am having trouble getting my calculations to execute at a reasonable speed. I have an object whose unknown location is modeled ...
1
vote
2answers
70 views

How to define a function $f(x)$ such that $f(1.5)=1.5$, $f(1.)=1$, $f(0.)=0$, etc.?

How to define a function $f(x)$ such that $f(1.5)=1.5$, $f(1.)=1$, $f(0.)=0$, etc.? Namely, if $x$ is an integer with a decimal point, $f(x)$ returns the integer only, otherwise returns $x$. This ...
0
votes
1answer
236 views

I don't understand ListCorrelate! [closed]

I want to solve a PDE equation (like Schrodinger equation) using finite difference in Mathematica. I don't understand what this code does! ...
2
votes
1answer
126 views

Convert frequency counts to long notation in Mathematica

I have a series of frequencies of values, e.g. 5 times 1, 10 times 2 and 5 times 3, as in list={{1,5},{2,10},{3,5}} and I would like to convert this to long ...
3
votes
1answer
120 views

Is it possible to get AltGr key to work in Math.exe?

For some reason when you run Math.exe form windows command line, Mathematica disables the AltGr key. This is a bit annoying since my keyboard locale has the keys [, ], {, }, @, $, \, | located under ...
0
votes
2answers
130 views

How to partition three years of data into daily samples

I'm trying to find mean of temperature data list. The temperature data list has 3 hours steps which means I have 365*8=2920 temperature measurements per year. My data are temperatures of 13 years. ...
0
votes
1answer
242 views

predator prey model with prey refuge

I want to plot the phase diagram of prey predator versus prey refuge to see how the prey refuge influences the population of prey and predator.And this is the system $x'=\alpha ...
1
vote
1answer
68 views

Mathematica quits calculation automatically

I have this little program that is adopted from a Wolfram demonstrations project (link here: http://demonstrations.wolfram.com/PercolationOnASquareGrid/). I want to see what happen if I increase the ...
-1
votes
1answer
136 views

Mathematica Compute Time Is Extremely Long (Integrate simple function with parameter scan)

I was wondering if you can help. I have a set of equations I need to solve for a list of parameters; entering each parameter value and solving anew each time is simply not economical. I found a way ...
3
votes
1answer
94 views

Why does Mathematica list the variables in a double integral backwards? [closed]

I am an advanced novice Mathematica user and have done a fair amount of single-variable calculus things with it. This semester I am using Mathematica for multi-variate calculus and when I tried to ...
1
vote
3answers
167 views

Plotting a frequency function

I have a list of numbers and I want to plot the fraction of numbers >= k against k which will naturally be a decreasing curve. How do I do that?
6
votes
1answer
275 views

Coloring a honeycomb structure

I am trying to generate a honeycomb structure. With the help of this MMA.SE question & this website, I got ...
1
vote
1answer
124 views

Help to solve the equation with RungeKutta method [closed]

I need to solve this equation. v'[t] + v[t] == 1/(1 + Exp[-v[t]]) I tried to solve it using RungeKutta method described in Wolfram ...
2
votes
0answers
95 views

Setting an initial value for ListAnimate?

ListAnimate is fairly similar to Manipulate, but while Manipulate has a simple way to request an initial value for the manipulation parameter, I haven't found a way to tell ListAnimate to start with a ...
3
votes
1answer
130 views

How can I get precise frame rates in dynamic?

I've been the Spritz sdk in my ios apps, and I love it. For funsies I wanted to see how much less code a mathematica version would take! Using dynamic I get a nice result, shown below in code. ...
0
votes
2answers
285 views

Are solid spherical harmonics implemented in Mathematica?

In certain applications, solid spherical harmonics can be very useful. They are essentially the usual, 'surface' spherical harmonics, with the appropriate power of the radius inserted: ...
3
votes
2answers
438 views

Package for representation of groups (group theory)

I wanted to know if there is a package which allows to compute representations of a group like the definition representation, adjoint and so on (for example the Pauli matrix for $SU(2)$ if I specify ...
0
votes
1answer
82 views

Creating If statements programmatically [duplicate]

I want to write an algorithm that returns a sequence of numbers, starting from a specified point but stopping once a criterion has been reached. For example ...
1
vote
0answers
37 views

How can I select two lists from a list of lists so that I receive the system of equations has only rational solutions?

I want to make a sytem of equations has the form $$\begin{cases} a_1x^2+b_1y^2 + c_1xy+d_1x + e_1y+3=0,\\ a_2x^2+b_2y^2 + c_2xy+d_2x + e_2y+3=0. \end{cases}$$ so that the given system of equations has ...
1
vote
1answer
70 views

Solve never terminates with simultaneous equation set

I have the following set of simultaneous equations that I want to solve symbolically. The two unknowns are $a$ and $d$. $a=\frac{c*(d/10)}{1 + (f/130) + (d/50)} - \frac{a}{1 + (a/100) + (d/100) + ...
0
votes
0answers
78 views

Solving a single equation with multiple parameters

If I wanted to solve equations like Cos[x]^2 = A Cos[Bx + C] + D what function should I use? The Solve function seems to only solve for as many variables as there are equations. Please note that my ...
0
votes
0answers
30 views

JacobiCN inaccuracy

For my calculations I need JacobiCN[s,k] for s near 0 from the left and k near 1 from the ...
2
votes
1answer
158 views

Showing ListLogPlot and redrawing FrameTicks

I want to combine two ListLogPlot plots. For example ...
1
vote
1answer
101 views

Connecting to a SQL Server Instance

What is the syntax for connecting to a specific instance of a sql server database? Here's my code: ...
0
votes
1answer
215 views

How do I keep my Animate running at high resolution?

I'm building an Animate where I have a 3D plot with some of its parameters changing: ...
-1
votes
1answer
81 views

MANIpulate. How to put labels and fit 24 vslides in a row? [closed]

How could I fit 24 vertical slides in a row?, in the up and How to add any reference like 0 and 8 ? and how to add 2 options boxes in the right under the vslides (or to the right of vlides??? What ...
0
votes
1answer
37 views

Generate array of every $n^{th}$ integer between two bounds [closed]

I want to generate the series {1930, 1934, 1938, ..., 2014} with Mathematica. I found that I can use Sum[2014-m*4, {m, 20}] to ...
7
votes
1answer
133 views

Equivalence under common permutations

I have lists which consists of sublists of equal length. The outer list is regarded as a multiset (that is, permutations of the sublists don't matter, but repetitions do), but the order in the ...
2
votes
1answer
1k views

Running a shell script within Mathematica

The title pretty much explains it and I have not found something similar already posted. Perhaps I am not searching for the correct title or maybe this is something very basic, but I would appreciate ...
1
vote
1answer
113 views

Mathematica does not respect tensor order?

I'm trying to verify an identity involving symmetric traceless tensors over the reals. What I tried was: ...
3
votes
2answers
122 views

Interpolation impossible for ListPlot with Missing?

I have a list of data to plot. I would like to plot them with lines but delete some data before plotting and leave the lines disconnected where data is deleted. For example, ...
3
votes
3answers
105 views

Name scope confusion

Sorry for the too ambiguous title. First consider a following code snippet. ...
2
votes
1answer
137 views

Country borders and grids with CountryData plot?

I am coloring several countries in the manner of the following: ...
30
votes
9answers
5k views

Programming paradigm change

I'm new to Mathematica, I've been learning by myself, and, being a Java developer for some time, it makes it hard to adapt. I've tried to solve a Reddit challenge, and I came up with this solution: ...
0
votes
1answer
213 views

marking the points of x-intercept on a plot

OK, I have a nice plot of some oscillating motion. I can read some stuff off the graph, but I thought it would be cool to show a dot where the curve hits the x-axis and a little label showing the ...
1
vote
1answer
98 views

How do assign an interval of values to a variable in order to use them in a function?

From my code (below) I have K1 and K2 set to zero in order to test this numerical method. However, K1 is on an interval from 0 to 32, and K2 is on an interval from 0 to 8. I would like to know if ...
3
votes
2answers
70 views

Mathematica: Extract the piece that contains x=0 from within a piecewise function

In mathematica, I have a piecewise function similar to: Piecewise[{ {x^2 + 2*x - 4, 0 <= x <= 1/4}, {0, true} }] I don't ...
5
votes
2answers
100 views

RLink Java(TM) platform has stop working

I am trying to send to R a big function,it has only three variables but output is quite big.So when i "translate" that code from mathematica to look like R code and input it in REvaluate i get the ...
8
votes
3answers
226 views

Graphics in Notebook Different from Graphics Expression?

Consider the expression TreeForm[a+b^2+c^3+d] which displays as This is a nice Graphics object, as I can prove by typing ...
3
votes
1answer
560 views

Converting truth tables to boolean expressions

I have a truth table for a Boolean expression represented like this ...
7
votes
1answer
349 views

Symbolic scalar-by-matrix derivative

Let's say I want to calculate the following scalar-by-matrix derivative $$\frac{\partial}{\partial A} \text{tr} \left[(\vec X^T A)^T (\vec X^T A)\right],$$ with $\vec X$ and $A$ being a $n \times 1$ ...
1
vote
1answer
110 views

A simple expression which Mathematica will not simplify

Sorry for the vague title, but I wasn't sure how to phrase this. I was using Mathematica to solve a fairly simple algebraic equation, but when I tried to substitute the solution into the original ...
-2
votes
1answer
79 views

How to put the labels in the minimun and maximun option in the slide verticals? Manipulate

I like this, but.. .. how could I put the labels to know +- over where value I are moving? for examples, between 0 and 8. ...
-1
votes
1answer
45 views

Are there a function to choose the greatest value in a discrete function? [closed]

Supose a discrete function show 1st, 2nd,...6th value are h = {5, 4, 2, 8, 9, 1} And I want to find the maximun in the subset of indexes 1,3,5,6 (what are ...
12
votes
3answers
168 views

What kind of check does DirectoryQ exactly perform?

I'm using Mathematica 9.0.1 on Windows XP and my drive letters are assigned as follows: C: and D: are hard local disks, while ...
1
vote
1answer
45 views

How to make 3 parameters selection and then execute, and not with each selection?

Manipulate[{u*v}, Row[{Control[{u, 0, 1}], Control[{v, 0, 1}]}], ControlType -> VerticalSlider, ControlPlacement -> Up] Q1.- How to select the operation ...
4
votes
1answer
250 views

Solving a nonlinear, second order d.e. in Mathematica

I am trying to solve the following differential equation $$ s''(x) = \frac{8}{9}s(x) -2s^2(x) + s^3(x), $$ with boundary conditions $s(-30) = 4/3 $ and $s(30)=0$, in Mathematica by using the following ...
2
votes
1answer
124 views

Opening notebooks from Workbench on Mac OS X?

I recently switched from Windows 7 to Mac OS X 10.9.2 for Mathematica development, and have set up Mathematica 9.0.2 and Wolfram Workbench 2 (running under Eclipse Kepler). Most everything works ...

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