0
votes
2answers
187 views

Absolute value and argument of a complex expression

I would like to find the absolute value and the argument of the expression: $ x + \sqrt { x^2 + y^2 } $ under the assumption that the absolute values of $ x $ and $ y $ are equal. I have written: ...
1
vote
1answer
100 views

Integrating a function forcing parameters to be real and positive

I'd like to integrate the function $f(x)=x^{a-1}e^{-b x}$ over the interval $[0,\infty)$. f[x_] := x^(a - 1)*Exp[-b*x] Then: ...
2
votes
3answers
438 views

Tracking iterations of a function

I'm learning MMA with Wagner's book. On page 41, he uses this to display the iterative steps of a FindRoot. However, I can't seem to replicate this (code at end), perhaps due to the difference in MMA ...
30
votes
8answers
2k views

Longest path in 0/1 matrix

I have a matrix of 0's and 1's forming a number of disjoint paths:   I would like to find the lengths of the paths, and from that "spectrum," the longest length (in the above example: 27, ...
3
votes
1answer
313 views

Map of all graphs obtainable with GraphData?

I've been trying to put together an answer to another question, but I am stuck, so I decided to post this question instead. Mathematica contains (among its curated data) information on definition, ...
0
votes
0answers
70 views

Computing integrals with differential operator

I've to compute this expression $$ \hat{H} = \frac{1}{4}g_2\int d^3R\int d^3r\ \bar{\Psi}(\vec{R}+\frac{\vec{r}}{2})\bar{\Psi}(\vec{R}-\frac{\vec{r}}{2})\left[ \delta(\vec{r})\nabla_{\vec{r}}^2 ...
5
votes
2answers
138 views

Generating EventHandler using Table

I would like to change the edge color of a graph when double clicking on it, the following code works: ...
1
vote
0answers
206 views

NIntegrate (multi-dimensional integral)

I am interested in the numerical evaluation of the following integral: $\int \prod_{i=1}^n dx_i \delta(\sum_{i=1}^n x_i) \prod_{i=1}^n f_i(x_i)$ where $f(x)$ is a complicated function. Unfortunately ...
2
votes
2answers
336 views

Making a flag with six vertical stripes

A flag is to be made with six vertical stripes by using colours yellow, blue, green and red in such a way that no two adjacent stripes should have the same colour. In how many ways is this possible? ...
3
votes
2answers
248 views

Integration and Fourier transform

I would like to calculate the distribution function from the characteristic function. There is a formula given as $$F_X(x)=\frac{1}{2}+\frac{1}{2\pi}\int_{0}^\infty \frac{e^{i w x}\phi(-w)-e^{-i w ...
5
votes
2answers
819 views

Calculating the area under a curve, but above a certain threshold value

so here I am with a time series of data (hours (t) and corresponding measurements (a)). ...
3
votes
2answers
241 views

How to improve visualisation of trajectories in 3D space

I have a list of trajectories from a bunch of photons that travel inside a scattering medium. Each trajectory is a list of $(x,y,z)$ pairs. I'd like to visualise them in 3D space. I came up with the ...
1
vote
1answer
109 views

Real and imaginary parts of a complex number

I would like to find the real and imaginary parts of $x + y$ in terms of polar coordinates. Here is code: ...
3
votes
1answer
76 views

FunctionInterpolation error when specifying AccuracyGoal

In the help page ref/message/FunctionInterpolation/ncvb, it is mentioned that one should specify AccuracyGoal for some (even ...
1
vote
1answer
89 views

Tooltips and points don't show when only 2 points in ListPlot?

Problem with ListPlot when each point has a Tooltip and there are exactly two points(or for a multi-plot ...
2
votes
1answer
79 views

How to map HoldForm?

I'm trying to compare between Sqrt[3.] and Sqrt[3]. To display the result, I mapped HoldForm to display the expressions on the left hand column (code at end), but it seems like Sqrt[3.] had been ...
1
vote
0answers
221 views

what is the best package/way to insert Mathematica code in latex docs?

I know that this question is not about strictly mathematica issue, but I think that in this site should be many pepople that use latex to distribute mathematica source code/examples. If the moderators ...
1
vote
1answer
130 views

Dynamically updating linked Manipulate variables

I am trying to write a simple cylindrical tank design notebook. Once the user inputs the desired capacity in gallons, it will compute the required volume (in cubic feet) and then offer sliders for ...
3
votes
1answer
191 views

Improving ListContourPlot mesh triangulation

I have a irregularly placed measurement data. I bring here a small example. I am sorry for that. mdata = {{20., 1.6, 0.218084}, {4.02807, 1.71068, 0.227565}, {19., 1.6, 0.240074}, {18.8333, ...
0
votes
1answer
300 views

Generating a list of standard normal random variables

Im trying to generate a list of random (standard) independent normal variables. For this, I first generate a random list of, say, 100 real numbers in the range [0, 1000], and then make them standard ...
0
votes
1answer
143 views

Inverse of a restriction of a non-invertible matrix

Let $A∈R^{4×4}$ be a non-invertible matrix, with $2$-dimensional kernel. How can I compute the inverse of the restriction of $A$ on a subspace where it is invertible: $A^{-1}v \,\,\,\,$ where ...
0
votes
0answers
24 views

How can I give input to an ArrayPlot [duplicate]

I would like to create a dynamic ArrayPlot so that the squares, when clicked, provide input. Can I use ArrayPlot for this? Or is there something else I should have to use.
3
votes
2answers
147 views

Is it possible to specify the direction of rotation in VectorAngle function?

If I use the function VectorAngle[{1,0},{1,-1}], is it possible to obtain the angle generated by rotating around the axis counter clock wise? In other words, I would move from the first vector to the ...
2
votes
1answer
80 views

Registering/detecting an importer by file name extension

I've developed an importer and exporter for FreeSurfer's MGH/MGZ file format; the specific format isn't important, but I was ...
0
votes
1answer
178 views

How can I obtain the complex root of an equation with FindRoot

I want to obtain the complex roots of some equations that are similar,but each of them has a different condition. this difference is the value of α in these ...
2
votes
0answers
45 views

Timing of ParallelDo versus Do: simple example [duplicate]

I'm trying to understand why a simple do-loop takes substantially longer when done in parallel than sequentially: ...
4
votes
2answers
97 views

Function pattern to support listed and non-listed arguments [duplicate]

I often want to write functions that take as an argument either a) a rule or b) a list of rules. As an example, when using Replace with just one rule, it does not ...
2
votes
1answer
109 views

ParallelEvaluate: Evaluation Rules and Increment

I'm trying to understand how ParallelEvaluate works, considering the two following snippets: ...
0
votes
1answer
43 views

Bar legend does not display values

My BarLegend shows only zeros instead of right values and I cannot find the reason. I set following minimum and maximum: ...
3
votes
1answer
188 views

How to generate a random binary tree with a given number of vertices and with a given shape, namely compact or elongated

I tried to generate a random binary tree with a Table of RandomInteger and to give a shape with a ...
0
votes
1answer
83 views

User defined output forms

I have a mathematica program which performs some manipulation which I then want to continue in another language, as I already have some code written in it. Syntactically this language is very similar ...
0
votes
2answers
115 views

how can tangent half angle substitution be done in Mathematica?

Is it possible to replace sine and cosine in terms of tangent half-angles and again the tangent half-angles by a variable say t?
1
vote
3answers
135 views

Collapsible Group of Control Objects

I did what I believe was a thorough search on this topic, but still ended up fruitless. Apologies if there is a trivial solution to this. Is there a way to group control objects together to form ...
1
vote
1answer
106 views

LiftingWaveletTransform with irregular grids

One of the properties mentioned in the literature about the lifting wavelet transform is that it can be applied on irregular meshes or grids (i.e. not equally spaced samples); but I don't seem to see ...
17
votes
2answers
424 views

Visualization: elliptical insights into data sets…

I was recently reading the following paper on visualization techniques using ellipses to gain statistical insights. Elliptical visualization for looking at correlations has briefly been touched on ...
2
votes
4answers
128 views

multiple sequential definitions, defining own set function

I want to define a function for doing multiple definitions, where I apply the same function f to all values, and definitions are done not at the same time but after ...
0
votes
2answers
186 views

Solving a system of equations using matrix form

Please bear with me as I am a beginner at Mathematica. In the following system, all variables on the right hand side are known, except for w1, ...
5
votes
4answers
247 views

BoxWhiskerChart without whiskers

I would like a chart showing the median, 1/4, 3/4 quartiles, without the whiskers or fences. how can I achieve this? I cannot figure out how to turn off both the whiskers and the fences in the result ...
3
votes
2answers
166 views

Plotting: DensityPlot produces artifacts

I am trying to plot the electric potentials of bouncing balls using the following code: ...
1
vote
0answers
217 views

How to find a particular solution using NDSolve

I'm looking for a way to find a specific solution to a differential equation. As a simplified version of my problem, here's a similar setup for a simple harmonic oscillator problem. ...
-3
votes
1answer
81 views

Finding integral bounds

i have this integral shown below is equal to 1, and i need to find "a" on mathematica, but I'm not sure how. integral (from 0 to a) sqrt((-50.8938 sin(8.4823 t))^2+(4-11.3097 sin(11.3097 t))^2) dt = ...
6
votes
1answer
145 views

Smarter way of manipulating plot style?

Say, I have a colorlist listColor={Black,Brown,Red,Cyan} Now, I have some Plot function that I can use this list: ...
0
votes
1answer
149 views

NIntegrate: Catastrophic loss of precision

Below is a simplified code that I am trying to evaluate. I am basically getting the rms value of a Wakefield function. When I finally try to evaluate the rms, I get an error. Any help would be greatly ...
0
votes
0answers
59 views

Showing Steps of Calculations [duplicate]

I'm solving a a differential equation in Mathematica and was wondering how to show the steps, like how Wolfram|Alpha does it, in the program. Any ideas?
6
votes
1answer
290 views

What is wrong about Abs[x]-a? Is it a bug?

Why is the Out[74] not {1 - a, {x -> -1}}? ...
1
vote
1answer
498 views

Find all roots in the interval of nonlinear equation

I am struggling on how to find all the roots of 1+1/2^x+1/3^x==0 which lie in a given of real and imaginary interval. Solve ...
0
votes
0answers
82 views

Timing Differences

In More efficient implementation for comparing coefficient lists in a Do-loop link, george2079 posts in his first answer a piece of code that takes 352 seconds to compute. When I run this same piece ...
3
votes
1answer
67 views

How to wait until a Listen mode link gets connected to?

Suppose we create a link like this: link = LinkCreate["mylink", LinkMode -> Listen] How can we wait until this link gets connected to by another process, and ...
0
votes
0answers
95 views

Solving for variables that satisfy an equation

I have the following ...
2
votes
2answers
155 views

Looking for an elegant way to solve a (system of) ODEs/functional equations with undetermined coefficients

I want to solve an ODE using undetermined coefficients/guess-and-verify and am looking for an elegant way to use this technique. I am running into a few ugly warts. Here is a basic implementation for ...

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