# All Questions

266 views

### Where I can find the CD version of Stan Wagon - “Mathematica in action” 3rd ed. book?

I've just started my license and I need the code to focus on implementing my programs. I can't make the code in the book run. Can anyone help?
521 views

### How to change the position of the PlotLabel? [duplicate]

PlotLabel positions the label on top of the plot by default. I would like to put it below the plot. How can I do that? Thank you.
81 views

### NDSolve : Solve a single variable-coefficient ODE as series of constant-coefficient ODEs [closed]

I have a manipulator equation of the form: $M(q){q''} + C(q,q')q'+G(q) = {0}$ where $M, C$ are $6$ x $6$ matrices, and $G, q$ are $6$ x $1$ vectors and $q$ a function of time. ...
104 views

### EdgeForm with Graphics

I want my figure to have an edge and I am playing around with EdgeForm[Thick], putting it in different places. My figure is: ...
71 views

### Obtain constant from DSolve [closed]

I need to extract constant C[1] from expression which I get when solve equation. i.e. DSolve[y'[x]==1/(2x),y[x],x] In result Mathematica gives me this one <...
112 views

Often when I'm writing a project in Mathematica, the number of arguments I must provide to functions spins out of control. I need a sort of object-oriented encapsulation approach. I've already had a ...
128 views

### Is there an elegant way of delaying evaluation of A==B when calling a function that uses this pattern

Suppose I wanted to define a number of functions that accepts expressions of the form: ...
656 views

### How to create a thick spiral then extract the coordinates from the image?

___________________ FOLLOWUP TO THE QUESTION : _____________________ Does anyone know how I could quantify the thickness of the spiral AND the thickness of the empty space between the arms? I know ...
214 views

### Find the area of a contour surface plotted by ContourPlot3D

I am looking for a way to find the surface area of a contour from ContourPlot3D. Here is an example where I might like to find the area of the contour surface to <...
637 views

### Trainable WEKA segmentation of images

Is there a Mathematica equivalent of Trainable WEKA Segmentation as implemented in Fiji, the image processing software? A Google search did not return any relevant links. I attach the original image ...
34 views

### How to get simultaneous eigenvectors of commuting matrices? [duplicate]

So let's say there are two square matrices A and B that commute (AB-BA=0). This implies that there must exist some complete set of vectors that are eigenvectors of both A and B. Is there any way to ...
93 views

### What options need to be set for Simplify to perform a certain manipulations similar to FullSimplify?

Simplify performs algebraic transformations and is fast, while FullSimplify tries a wide range of transformations involving ...
105 views

### Evaluate NDSolve within NDSolve

So I am attempting to solve a differential equation which includes a differential equation (i am not sure if this why my code is giving problems). I am pretty sure that everything is as its supposed ...
49 views

### How to get Complement function working in a For loop? [closed]

I've been working on a piece of code that will delete small components from a nested uneven matrix (n pages, n rows, 3 columns), by deleting the pages with less than ~30 rows. However, I've notice ...
47 views

### Can I rely on the ordering of the adjacency matrix? [closed]

Suppose I have created a Graph[{1,2..n}, {1->3, etc}], and I take the adjacency matrix of that graph. Can I rely on the fact that the i-th entry in the graph is the i-th node in the matrix? Or maybe ...
58 views

### Does a matrix need to be rationalized when calculating MatrixExp? [closed]

I have a sparse matrix, L, and need to calculate its exponential, MatrixExp[L t], where t is ...
272 views

### Having trouble translating Matlab fsolve into Mathematica

I searched the site and found that someone said FindRoot is equivalent to fsolve, however, without proper options, ...
89 views

### Simple ways to implement vector dilation

Suppose we have a singly connected but not necessarily convex polygon. Something like shape = CountryData["Chad", "Coordinates"]. Is there a simple way to ...
105 views

### How to freeze and test a list of programs?

I have a list of problems for my students and I'm trying to use the new v10 feature TestResults like so: ...
53 views

I am trying to solve a system of differential equations. ...
305 views

### Import data from excel and store it permanently in notebook

I am trying to write the code for doing the following: by clicking a button, import specific data from an Excel file which I select through a dialog window; input a name for the imported data set ...
287 views

### Why don't the arrowheads show for this directed graph?

Bug introduced in version 9.0 or earlier and fixed in 10.3 It's very weird, but the first graph is shown as undirected (dots connected by lines, not arrows. The second is shown as directed, with ...
122 views

### Assign values to parameters from a list/Matrix using GUI

Assume there is a list like: ma={{L1,r1},{L2,r2}}; I want to convert the ma to a GUI which asks me about the values of L1,r1,...
105 views

### problem exporting an Animate video

Here's my code: ...
85 views

### Customized FortranForm output

Let's take the following example V = (-G*Mn)/Sqrt[x^2 + y^2 + z^2 + cn^2]; Vx = D[V, x]; FortranForm[Vx] The result is ...
355 views

### Implicitly defined compact complicated surface

A Seifert surface for the (3,4) torus knot is defined by the intersection of $S^3 \subset \mathbb{C}^2$ with the set $\arg(z^4-w^3)=0$. The boundary is at $z^4=w^3$ and this is the torus knot. Here ...
163 views

### Export NDSolve results

I can see the correct result of my NDSolve when I plot them with large PlotPoints. ...
743 views

### Calculation of 2D FFT for an image

I am trying to obtain 2D FFT of an image. From the 2D FFT, I wish to calculate the amplitude of the FFT averaged over a circle vs the distance in pixels by varying the radius of the pixels which is ...
553 views

### How to solve the following fourth order partial differential equation including Laplacian

I wish to solve the following fourth order partial differential equation including Laplacian with the boundary conditions with the initial conditions ...
131 views

### Initializing several values of a function

How do I initialize several values of a function at once? Consider the function f[0] := 1; f[1] := 2; f[2] := 3; f[n_] := f[n] = f[n-1] + f[n-2] + f[n-3]; Is ...
51 views

### Why is the Max function so slow when operating on lists of dates?

Example: dates = DateRange[DateObject[], DatePlus[DateObject[], 15]]; First[AbsoluteTiming[Max[dates]]] (* 21.364247 *) As a workaround, ...
151 views

### Calculate area from RegionPlot directly

I have a region plot, and I would like to calculate the area: ...
140 views

### How to Optimize Solution? (Project Euler #14) [duplicate]

Link to Question: https://projecteuler.net/problem=14 I began by defining the following functions below. ...
146 views

### AppendTo or Part in a ParallelDo?

I have a question regarding how memory is managed in parallel. Specifically, I'd like to know what is the better practice when constructing an array within a ...
204 views

### Defining a function implicitly and calculating its derivatives

I'm interested in using Mathematica's symbolic manipulation to obtain, for a particular function $f$, derivatives of arbitrary order evaluated at zero. Normally I'd use the ...
70 views

### A single point moving at different speeds through different regions on a plot (Manipulate)

I've been working on this for a while with little success. I have a point (that needs to be connected to a Manipulate control in some way), that moves up the plot ...
218 views

### Reject diverging solution of NDSolve

I'm trying to numerically simulate a spring system with complex stiffness. In essence systems of the form $x''(t)+ (a+ ib) x(t)=0$ For this simple example an analytic solution is easy to find. The ...
381 views

### How I can integrate $\int_0^{a} x e^{-\frac{b^2 x^2}{2 c}} J_0(n x) dx$?

How can I get a solution to the integral given below ? $\quad \quad \int_0^{a} x e^{-\frac{b^2 x^2}{2 c}} J_0(n x) dx$ where $a,\,b,\,c$ and $n$ are constants and $J_0$ is a Bessel function of the ...
139 views

53 views

### A question about the syntax [closed]

I have $3$ elementary questions to ask and I thank you in advance. Question N°1. What is the right syntax for $$y\equiv0\pmod {2}$$ in the code below? ...
189 views

### Factoring the imaginary unit

Suppose you have this: Collect[2 u + I + 2 + I,I] It gives the same. Is it possible to factor I in elegant way (not manually)...
200 views

### NonlinearModelFit errors and precision

For this problem, I use a data set, which I've made available here. ...
98 views

### FullSimplify not giving me a physically useful answer for Mott scattering

I am using Mathematica to find the cross-section for Mott scattering over an extended target. I evaluated ...
37 views

### exporting 3D graphics in STL format (for 3D printing) [duplicate]

How do I set the size of the exported item? (Graphics3D has no implied unit, so it is not a-priori clear what size the object will be, and experiment indicates that ...
156 views

### How to use Wolfram language in an external program with low latency? [duplicate]

Im using Wolfram language on Pi B,and I want to compile a '.m' file (like "test.m" that contains Wolfram functions), in an external program like a C/C++ and then Export the output in an image file ...
176 views

### Given a matrix of integer, create a matrix with 1 or 0 according to which numbers are in the first matrix

Not sure the title gives the idea of what I need, so here is a sample: I have ten (w) combinations (subsets) of 20 (n) numbers taken 4 (k) at time. I need a matrix of dimension w x n with 0/1 in each ...
137 views

### Split/unmerge merged cells in notebook file

I have merged cells in a Notebook file. Is there a way to split such a merged cell group back to single cells, in each of them being one command?
70 views

### NSolve not solving [closed]

I've been working on a Newton Cooling equation problem for my diff equ class and cannot get NSolve to solve this equation. I've plugged it into Wolfram Alpha and my ...