0
votes
0answers
243 views

Defining extra boundary conditions for NDSolve?

I have a second order reaction / diffusion type ODE of the form $\frac{D_{o}}{r^2} \frac{d}{dr}\left(r^2 \frac{dC}{dr} \right) - \frac{aC}{C+k} = 0$ where $a, k$ and $D_{o}$ are constants and $C$ is ...
1
vote
0answers
160 views

How to prevent simplification of hypergeometric functions resulting from integrations?

Definite integrals from 0 to Infinity over a product of two hypergeometric (including exponential, trigonometric, hyperbolic, ...
0
votes
0answers
51 views

Simplify symbolic expression in terms of constants [duplicate]

Say I have an expression $a+b+a\times b$ and I define $c:= a\times b$. How do I get Mathematica to write $a+b+a\times b$ in terms of $c$, i.e. $a+b+c$?
1
vote
1answer
232 views

Print indexed (by subscript) variable name systematically

I have some variables : Subscript[S, 1], Subscript[S, 2]...etc. But they are defined in a for loop like For[g = 1, g < 4, g++, Subscript[S, g] = g]; Later, I ...
16
votes
2answers
537 views

Efficient priority queues?

I'm trying to figure out how to transfer the concept of a priority queue to the functional world. Searches have turned up some implementations that use Append and other expense list copying ...
0
votes
1answer
138 views

fit recursive function to data

I have a function $g(x, n)$, which is a recursive expression: $x$ is a variable and $n$ the number of iterations. In my case $n=3$ for all $x$. An example is the following: ...
7
votes
1answer
299 views

How to make dynamic input fields work with drag & drop

I have an application using InputField to allow a user to dynamically update a data structure. In some cases the user will want to remove a string from one field ...
3
votes
1answer
200 views

How can I highlight and individually color the connected components of a graph?

I have a graph G, and I wish to individually highlight and color the different connected components of a graph. It is simple enough to do this for one component: ...
1
vote
1answer
80 views

Append CellTag to list of Cells

As suggested in this earlier post, I restate my question here about appending CellTags option to existing list of Cells. What I ...
-1
votes
1answer
189 views

Linking two differential equations

The solution and plot of the Differential equation is $\frac{d^2S(r)}{dr^2}+\frac{1}{r}\frac{dS(r)}{dr}-S(r)+3S^3(r)=0$ ...
1
vote
1answer
80 views

SetOptions and Cell

I'm trying to change the CellLabel of Cells using SetOptions[Cell, CellLabel -> "test"] or ...
14
votes
3answers
1k views

show density plot on US map

I have a bunch of data points in the form of {latitude,longitude}. How can I plot their density on a US map? Single points on the map do not show clearly their ...
2
votes
1answer
124 views

Why the EuclideanDistance of these 2 exact points generates the warning N::meprec?

The two points are: pts = {{1/4 (-1 - Sqrt[5]), Sqrt[5/8 - Sqrt[5]/8]}, {1/4 (-1 - Sqrt[5]), -Sqrt[5/8 - Sqrt[5]/8]}}; EuclideanDistance @@ pts ...
5
votes
1answer
103 views

How can I execute a sequence of statements interactively?

I'm fairly new to Mathematica. Suppose I have the following function: f[x_Integer] := Module[{y, z, r}, y = 5; z = 10; r = x + y + z; r ]; and I ...
12
votes
3answers
504 views

WaveletScalogram in polar coordinates

For given dataset data = Re[Zeta[1/2 + I Range[0, 100, 0.01]]]; It is nice that Mathematica can plot data in both Cartesian and Polar coordinates. ...
2
votes
1answer
238 views

Change values in string under condition

how to change the width and height in the HTML code into some other values decided by ratio and a fixed width? The background is that you can adjust a image in ...
1
vote
2answers
98 views

HoldForm and RandomChoice

I'm trying to get random expressions displaying. For that, I'm starting with addition, multiplication, substraction and division. When trying out this code ...
11
votes
3answers
3k views

Implementing a dictionary data structure

As one learns from a course on data structures, hash maps or dictionaries can be efficient when applied to appropriate tasks. I need a hash map in Mathematica and I've never found it. I'm scratching ...
1
vote
1answer
185 views

Need better font control [duplicate]

Generally many programs have a menu item to raise/lower current font size. This is much more convenient than trying to root around in in internal mathematica options. I need to change ALL default ...
28
votes
1answer
432 views

Do Mathematica notebooks include personal metadata?

I am about to send a Mathematica notebook to someone and I would like to make sure it does not contain any information that could personally identify me. I would also like to produce pdf files from ...
2
votes
0answers
230 views

Clearing memory of a subkernel in a Do loop

I have a Do loop, which saves data directly to a .txt file. However when I leave it running for long periods of time the RAM ...
0
votes
2answers
282 views

LogPlot of the calculated data in For Loop in Mathematica

I have the following loop, for calculating a data for different values of inputs. How I can plot the result at the end of For loop? Its not matter if the plot is inside or outside the loop, I just ...
-1
votes
1answer
534 views

plotting the solutions of system of differential equations [duplicate]

The following code include the system of differential equations: ...
2
votes
1answer
86 views

Strange response with dynamic texture and MousePosition

I built a cubic, then use MousePosition together with GUIScreenShot to take a floating region with fixed size (200*200) on the ...
2
votes
2answers
91 views

How to make a function work on symbols in a specific context

Let us say we have two sets of symbols $(x, y, z)$ with the same names that live in two different contexts: ...
4
votes
3answers
337 views

SparseArray row operations

Given a large (very) sparse matrix, A, how can I efficiently "operate" on only the nonzeros in a given row? For example: For each row in A, generate a list of column indices that have a magnitude ...
6
votes
6answers
292 views

Sort a list of coordinates by frequency from first component of each coordinate

The situation is that I have a List like this: ...
-1
votes
1answer
112 views

Indicating the axes [closed]

I want to scale the $x$ axis of the plot by $x^0$ and the $y$ axis by $\tan x$. Is this possible ? Plot[Tan[x], {x, 0, 10}, PlotRange -> Automatic] EDIT: ...
10
votes
0answers
1k views

How to visualize Riemann surfaces?

In WolframAlpha we can easily visualize Riemann surfaces of arbitrary functions, can we plot the Riemann surface of an arbitrary function using Mathematica and ...
1
vote
1answer
191 views

Do any users know of methods to capture Twitter feeds and subject them to analysis? [duplicate]

I would like to use the output of about 300 Twitter sources and would probably collect 30 minutes of tweets at a time and subject each collection to analysis; ideally this process would be automatic ...
1
vote
1answer
101 views

FindEdgeCut with weighted graphs

If I want to find a minimum cut between two nodes in a weighted graph, I would use FindEdgeCut as follows: ...
7
votes
1answer
369 views

Adding/deleting weighted edges to a weighted graph

How can I add and delete weighted edges in a weighted graph? Using Graph in Mathematica I want to add a weighted edge to a weighted graph. The problem is ...
1
vote
2answers
80 views

Export with different address

Is it possible to use the Export[] command and add another address other than the usual Home directory that is used?
3
votes
0answers
69 views

Extending listability to coordinates [duplicate]

I noticed that one can subtract a since real number value from all elements in an array by writing something like {5, 4, 3, 2, 1} - 5 which outputs ...
0
votes
1answer
169 views

Are there built in functions to perform a geometric transform to rotate a set of points around an arbitrary point?

I have a list of points {{4,5},{6,7},{9,8},...} in two-dimensions. I'd like to rotate these points some number of degrees $\theta$ around an arbitrary anchor point ...
0
votes
1answer
380 views

Specify values for X-axis and Y-axis ticks and control their format

I have following problem: I want to set the values for the X-and Y axis by myself, but the values (e.g. 0.800) are not plotted as I defined them (see image 0,8), mathematica removes the zeros. ...
1
vote
2answers
306 views

How to pick a solution from a list of solutions using a test?

I have a list of solutions that depends on a parameter b3 and I'd like to get the solution for which the x value is minimal when ...
3
votes
2answers
183 views

Separating disconnected graph objects without losing vertex coordinate assignments

Say I have a graph Gtest, which has multiple disconnected components. I found that I can isolate individual components while retaining vertex coordinate ...
9
votes
1answer
113 views

FindHamiltonianCycle is not invariant to edge permutation

Found this bug-like behaviour today: if the order of edges is changed so that VertexList does not return the vertices in canonical order, ...
0
votes
1answer
35 views

Parsing output from FindHamiltonianCycle to recover an ordered list of vertex positions for a discovered path

After applying FindHamiltonianCycle to a graph, one generates output that looks like the following: ...
1
vote
1answer
91 views

StringForm and NotebookWrite

I'm trying to get my head around NotebookWrite for the last few days. I can't understand why ...
3
votes
1answer
358 views

Generating a graph object where vertices are pixel coordinates and edges represent two pixels being in the same Moore neighborhood

I have a list of integer pixel positions, pts, and I wish to create one or more graph objects where vertices at these pixel positions share an edge if they are ...
5
votes
2answers
1k views

How to extract data from contour plot as a text file?

I have the following expression from which I want to extract data for a contour plot. ...
1
vote
1answer
167 views

Generating a list of contour pixels for a morphological component

I have a set of pixilated shapes, and after transforming each shape into a morphological component, I want to be able to return the coordinates for pixels that lie on the contour of the shape. More ...
3
votes
3answers
246 views

How to find the numbers $a$, $b$, $c$, $d$ of the function?

I want to find four numbers $a$, $b$, $c$, $d$ of the function $f(x)= \dfrac{a x + b}{c x + d}$ satisfying the conditions $f(-6)=4$, $f(-5)=5$, $f(1)=3$ and $f(2)=2$. I tried ...
2
votes
1answer
245 views

How to fill between abscissa values?

How can I produce a fill (in a plot) that extends between two given abscissa values, and "infinitely" in the ordinate direction? (Of course, here "infinitely" just means "up to the top and bottom ...
0
votes
0answers
111 views

Matrices and Upper / Lower Triangular Factorizations

Does anyone know (I have searched documentation, online and MathSource) if there are ways to coax out the following factorizations from Mathematica? $A = LU$, $LU$ factorization $PA = LU$, $LU$ ...
1
vote
1answer
119 views

How to preserve focus on InputField after Print?

If you press Enter in the example below it should become clear that test is being adding to the textbox instead of the current ...
10
votes
4answers
1k views

How to keep markers as dots in a joined ListPlot?

Consider the following typical interactive sequence. First I produce a ListPlot: OK, not bad, but I want those dots to be bigger, and also joined. First, I ...
4
votes
4answers
1k views

Numerical differentiation methods

Is it possible to write a code in Mathematica that implements various differentiation methods (like forward, central, extrapolated, etc.)?

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