5
votes
2answers
186 views
How to graph a series of coupled oscillators and watch the wave move along them
Here are the differential equations that set's up the 11 coupled oscillators.
...
30
votes
3answers
519 views
Why are my plots displaying behind the axes?
I need to create graphs with light gray axes and black lines. All of my plots display behind the axes. How can I make the plots display over the axes?
...
1
vote
1answer
67 views
Differing behaviour of GeneratingFunction with different numbers of parameters
When given a single variable sequence, GeneratingFunction is automatically expressed in the most "direct form", for example,
...
1
vote
1answer
43 views
5
votes
1answer
302 views
Image of input and output cells is not exported correctly
Wolfram Blog uses PNG images to display input and output cells in a notebook. For example, the following is an image from Samuel Chen's post:
I should be able to produce a similar image by ...
-2
votes
0answers
66 views
Reduced Planck constant and UnitConvert to Erg * Second
I declared the reduced Planck constant by
ℏ = Quantity[1, "hbar"]
which worked. Now I want to calculate something in cgs units. Therefore, I tried to convert ...
3
votes
2answers
176 views
Create polygon using edge lengths and area
Four-sided convex land plots are usually denoted with edge lengths and area.
How do I create a Polygon Object with these parameters in Mathematica ?
2
votes
1answer
90 views
Reducing exponential inequalities fails
I am quite stumped by this problem :
Reduce[ N^(x-y) <1 && N > 0 , x, Reals]
gives the expected result
...
2
votes
0answers
62 views
How to efficiently count occurrence of some element in a list? [closed]
I have a list of numbers, for example:
list = {1,2,3,4,2,1,3};
what would be efficient way to count all occurrences of some number?
I tried so far:
...
1
vote
0answers
79 views
Shapley value and Mathematica [closed]
I use the TuGames package in Mathematica to analyze
cooperative games. Is it possible to calculate Shapley
value, Nucleolus, etc., for a large number of players like
400 or more?
0
votes
1answer
53 views
Forming product of function of prime factors
Given a list of numbers each containing 2 prime factors, I wish to make a list of the products of the logs of each factor. For example, given
L = {4,6,9}, I would like to form P = ...
10
votes
1answer
82 views
When is the output of examples in function documentation rasterized?
Upon building documentation in Workbench, Workbench sometimes converts the output of examples on function pages into rasterized images, and sometimes not. Does anybody know what controls this ...
2
votes
1answer
87 views
Problem with Sinc[x] function and rounding
I seem to be having some trouble with the Sinc[x] function, and I think it's due to rounding, but I'm not sure.
The code is below, with relevant constants:
...
1
vote
0answers
35 views
3D plot changes it's size while rotating [duplicate]
When I am rotating drawn 3D plot by mouse it rotates Ok until mouse release. After that it slightly changes it's size instantly. Probably it tries to accommodate document layout or something.
Is it ...
1
vote
1answer
65 views
NIntegrate converging too slowly when increasing size of array
I have a problem with a numerical integration. I have a 4x4x4x4 array that has for each entry an integral and I want to use NIntegrate to evaluate it. It gives me ...
1
vote
1answer
61 views
Rounding only reals in an expression containing, reals, integers and symbols
I am trying to make a function that would make rounding real numbers in an expression possibly consisting of real numbers, integer numbers and symbols. An example of such an expression is below:
...
2
votes
1answer
59 views
White spots in ListDensityPlot
I have a problem with ListDensityPlot.
I have some data on an irregular grid.
I try to plot them with
...
12
votes
3answers
1k views
How to do System dynamics simulations / diagrams in Mathematica?
System dynamics is an approach to understanding the behaviour of complex systems over time. It deals with internal feedback loops and time delays that affect the behaviour of the entire system. What ...
1
vote
1answer
161 views
Computing Correlations and p-values
I have two vectors $A$ and $B$ of length (say) $50$ or so, and I want to determine whether there is any correlation between their entries. I computed their correlation directly and found it to be ...
4
votes
3answers
358 views
Speeding up export of a matrix to a dat file
I'm trying to export a 1000*100 matrix of numbers to a .dat file using Export (I want the numbers to be separated by a tab) and ...
6
votes
2answers
115 views
Finessing labels in BarChart
BarChart is aggravating. Why don't the following correctly display both percentages and labels?
(1)
...
2
votes
3answers
122 views
Plotting the deformed shape of a rectangle
I want to plot a rectangle using graphics :
rc = Graphics[{Blue, Rectangle[{0, 0}, {1, 1}]}];
and add a deformation function to it:
$$\chi(\mathbf ...
2
votes
2answers
78 views
Plotting rainbow circle [duplicate]
I am trying to plot a parametric circle in rainbow colors. It should go round once, but I'd like to be able to make it go round the rainbow an arbitrary amount of times.
I currently have:
...
2
votes
2answers
106 views
Coloring a shape according to a function
I would like to create a $2D$ shape, say an ellipse, where each point in the ellipse is colored according a RGB function, so at point ...
-1
votes
0answers
35 views
Simplifying Expressions to minimize multiplications [duplicate]
I have a big matrix, whose coefficients mostly have the following form:
2*(Lz*q*q0+Ly*p*q2-Lx*q*q2+Lz*p*q3-Ly*q0*r-Lx*q3*r)
This was obtained with Simplify, with ...
0
votes
1answer
147 views
Integro-differential eqn with double integral
I am looking at the following variation of a integro-differential, with y[0]=1.
The output is not great, any solutions to this?
...
0
votes
0answers
46 views
Find leading-order asymptotic approximatons to the solution of epsilon y''+Cosh[x]y'- y == 0
I am trying to solve this boundary value problem and obtain the leading-order approximations using asymptotic matching. But I got my solution wrong and I am stuck along the way, struggling to find any ...
4
votes
2answers
74 views
Solution of equation with power series (perturbation)
So I need to use Mathematica to find the solution of $y=x- \epsilon \sin(2y)$ as a power series in terms of $\epsilon$. I'd assume I'd need to create an equation $f=x-y- \epsilon \sin(2y)$, then ...
4
votes
1answer
148 views
Solving an ODE in power series
How do I find a series solution to an ODE?
I do not mean taking the Taylor series of an exact solution; I want to solve nasty nonlinear differential equations locally via plug and chug. Surely, that ...
6
votes
2answers
165 views
1
vote
1answer
77 views
Find elements of a list which are empty
Sorry for the most basic of questions. How would I find the positions of a list of elements which are empty, for example I have the list
...
3
votes
0answers
50 views
How can I control the controlplacement of Manipulate?
I want to place the Slider of manipulate as I want but I can't, help me to get rid of it
...
4
votes
3answers
80 views
label all vertices in polygon plot
Let's say I have the following plot
Graphics[{Opacity[0.2], Rectangle[{0, 0}, {4, 4}]}]
And I want to label all vertices on the graph to give their coordinates, in ...
1
vote
2answers
65 views
Locator following other locator in DynamicModule
I'm trying to create a dynamic environment where I specify, using two locators, the initial condition (position (x,y) and velocity angle (alpha)) of a 2D particle.
To simplify, I'm assuming the ...
0
votes
0answers
34 views
Changing GeometricBrownianMotionProcess function
Since the function GeometricBrownianMotionProcess is given by Mathematica I have some technical questions. If we consider the following example:
...
3
votes
1answer
281 views
Efficient way to perform elementary integration step with NDSolve internal method
I'm trying to tweak the NDSolve function to perform one elementary integration step (using some explicitly selected stepping algorithm via ...
15
votes
5answers
818 views
Partition a set into subsets of size $k$
Given a set $\{a_1,a_2,\dots,a_{lk}\}$ and a positive integer $l$, how can I find all the partitions which includes subsets of size $l$ in Mathematica? For instance, given ...
13
votes
2answers
145 views
Problem importing URL with Greek characters
I'm considering buying a car. So I thought why not make a web-crawler in Mathematica to pile-up car data? Brilliant idea.
Then I found this Greek website, gocar.gr, which just so happens to have all ...
0
votes
1answer
68 views
Parametric Plot of coupled differential equations
I am able to plot a graph of all the differential equations, but I'd like a parametric plot of each individual one.
Here is what I have so far.
...
5
votes
1answer
85 views
Determining which rule NIntegrate selects automatically
I need to numerically integrate a highly oscillatory function over the semi-infinite domain $(0,\infty)$:
$$\int_0^\infty \frac{\sin^2(x) \sin^2(1000 x)}{x^{5/2}}\mathrm dx$$
Since the Levin rule ...
-1
votes
0answers
56 views
How can I rotate 3D objects using MSPManipulate?
I tried Manipulate in Mathematica for 3D objects and could rotate them freely. I tried the same in webMathematica by using ...
5
votes
3answers
134 views
How do I find the intersection of a closed 3D curve given by numerical data with a specified plane?
I have a list of 3D data points which form a closed curve. My own data can't be easily generated analytically, but the qualitative behaviour is well represented by a parametric curve families such as ...
0
votes
0answers
67 views
FindFit for dimension reduction?
Given an n-dimensional function, can I use FindFit to produce an approximate (n-k)-dimensional function?
Here is a simplified illustration of what I am trying to do. I have
$$f(x,a,b,\mu,\sigma) = ...
2
votes
1answer
392 views
2
votes
0answers
65 views
Finding and interpreting errors [duplicate]
This sounds like a fairly trivial question, but I can't think of any way to solve it. I am doing an extensive parameter sampling where a set of ODEs is used together with ...
0
votes
0answers
46 views
Interpretation of output derivative expression [duplicate]
I am trying to write Mathematica file to find Div, Grad, Laplacian, etc. in coordinates ...
4
votes
2answers
132 views
Getting RGBA data of an image with ImageData
What is going on with returned data in the following examples? It appears ImageData returns different types depending on the what data is passed into ...
3
votes
1answer
87 views
What's the main difference between FindClusters and ClusteringComponents? [closed]
In many cases, FindClusters and ClusteringComponents provide similar results. Options for hierarchical and agglomerative ...
0
votes
1answer
102 views
Maximizing trig functions in Mathematica
Just to give some context, my motivation for this programming question is to understand the derivation of the CSHS inequality and basically entails maximizing the following function:
...
2
votes
2answers
72 views
How to make BSplineFunction pass each data point and naturally smooth?
(Old package, works good)
...
