1
vote
1answer
195 views

How can we ensure the result of Mathematica is exactly correct?

This is an example, I plot a function and find it has a defect when x approximates 400. Plot[Cos[.3 x] Exp[-0.01 x], {x, 0, 1000}, PlotRange -> All] Another ...
0
votes
1answer
416 views

How does Mathematica interpret a expression?

I'm a beginner to Mathematica. I'd read several document. But I still have a problem. For example, every expression in Mathematica are of the form ...
1
vote
1answer
108 views

How can I define a function that takes a list of reals?

I'm trying to define a function f which takes a list of reals. My purpose is to build a function which I can give a list of reals, integers or strings and have it ...
0
votes
1answer
122 views

Matrix operations performed with column-vectors

We have 3 matrices: m1, m2 and b. We want to apply matrix operations (dot or sum) in a ...
6
votes
2answers
295 views

How can I create a class of matrices programmatically?

I am trying to figure out how to create a function that can create the matrix pattern below, where: f[1] returns {{1}} ...
39
votes
1answer
3k views

What is the relationship between Mathematica and Wolfram Desktop?

I'm confused about the differences among various Wolfram products. In particular what is the relationship among Mathematica, Mathematica Online, Wolfram Programming Cloud, and Wolfram Desktop? Are ...
6
votes
2answers
199 views

Why the Mouse dragging response not as smooth as Locator

I am experimenting to use MouseDragged eventhandler to change the vertices positions of a triangle, it works, but not as smooth as using Locators. Is this the ...
8
votes
5answers
1k views

Export high resolution figure causes missing ticks

I understand that Mathematica has a bug when exporting images. The ticks are scaled not correctly when exporting at high resolution. For example: when you do: ...
2
votes
1answer
220 views

Using FortranForm

I need to use in Fortran, matrices that I create in Mathematica, therefore, I need to format them, so that Fortan can understand them. I focus on the simplest example: Let's say I have tha matrix A ...
1
vote
0answers
104 views

Historical Prices via FinancialData

I downloaded the historical stock prices for some stocks in the period 1990-2013 via FinancialData some months ago and computed the financial returns. Now I downloaded the data again for the same ...
2
votes
2answers
261 views

Measures of association, Concordant and Discordant

I want to calculate concordant and discordant pairs on nx2 tables. ...
1
vote
3answers
291 views

Defining a function as a sum of several Gaussians

I have a function that is a summation of several Gaussians. Working with a 1D Gaussian here, there are 3 variables for each Gaussian: A, ...
1
vote
1answer
464 views

Plot has red 'film', no error message

I am encountering really strange behavior: I wrote a function that plots values some data. After executing the code the resulting plot has the red 'error' colour, but only momentarily (maybe 0.1 sec). ...
4
votes
3answers
148 views

Creating nested matrix using random integers

How do i create 15x2 matrix with 2x2 random integer elements? My code only returned identical 2x2 elements:
2
votes
1answer
145 views

how to find iso-cost contours on a 2d plot efficiently

Consider a 2D plot in which dimension 1 and 2 represent quantity 1 and 2 respectively ranging over 0 to 100. Each point in the space corresponding to (x,y) represent cost of choosing quantity 1 as x ...
2
votes
2answers
208 views

Choosing a branch of the square root when performing a series expansion

I have the following problem. Consider expression f=Sqrt[(x-2y)^2] There is an obvious ambiguity in the definition of f ...
3
votes
1answer
663 views

HarmonicNumber problem

I am looking for all the roots of HarmonicNumber, in the domain [-30, 1] and [0, 6000] for the real and imaginary parts, respectively, and where the parameter ...
4
votes
1answer
147 views

The algorithm of ListGraphs[n,m]

I'm not sure if this is a Mathematica problem, math problem or a CS problem, so if this is off-topic please transfer it. In the package Combinatorica there is a ...
5
votes
2answers
823 views

How can I get the exact real solution of this equation?

I want to solve the equation Sqrt[x] + Sqrt[1 - x^2] == Sqrt[2 - 3 x - 4 x^2] with real solutions (in the real domain). I tried ...
11
votes
1answer
240 views

Extract what symbol is set by SetDelayed, Set, TagSet, UpSet, SetAttributes, etc

One of the recent features of the Mathematica Plugin for IntelliJ IDEA (www.mathematicaplugin.halirutan.de) is a Structure View which let's you see information about several definitions that are done ...
0
votes
1answer
87 views

Numerical integration with purely numerical integrand

I'm trying to perform a numerical integral with an integrand that should not be manipulated with any symbolic preprocessing whatsoever. Consider the following simple test : ...
2
votes
2answers
126 views

Multi-legend issue in ChartLegends?

Been fiddling around with the legends and trying to place one in each corner and I bumped into an issue: ...
6
votes
5answers
815 views

Write any positive integer as a sum of squares

With n = 17 I would like to get {4, 1} and with n = 999 {31, 6, 1, 1} so that, for example, ...
2
votes
1answer
492 views

Finding the eigenfunctions of one and two dimensional Harmonic Oscillator

(Edited) For finding the ground state wave function of: $ H\psi(x) = (-1/2)d^2\psi(x)/dx^2 + (1/2)x^2\psi(x) = E \psi(x)$ I have written: ...
1
vote
2answers
83 views

Compiling function with predefined expression

I'm using the Compile function in Mathematica to compute say the following : f=Compile[{x,_Real},Cos[x]] Then I can compute f[x] for x taking any real value. Ok, ...
5
votes
3answers
312 views

How to highlight the whole selected cell

Is there any way to highlight the whole selected cell? some times if I want to delete a certain cell and if the code is long and cells are without output, it is hard to know which cell that you are ...
2
votes
1answer
76 views

Defining a function (but not explicitly)

I have a question that must have a simple answer, but googling and searching this website did not produce an answer, so I'm asking it here. I'm working with three variables $x, y, \theta$, and I want ...
0
votes
0answers
108 views

Change Default Font Color of Commands [duplicate]

I encountered to two problems with Mathematica: one: How can I change the default font color of commands and functions in Mathematica (which is black) to another color, so that whenever I wanted to ...
1
vote
2answers
384 views

Loop until convergence of two variables

I have the following program which i need to repeat steps until until two variables converge and I want this to be printed with the number of iterations: What I have : Input variables: ...
1
vote
2answers
126 views

How to eliminate (hide) output numbers in a slide show

I am creating a slide show with several imbedded Manipulate objects. I can hide the Manipulate command by clicking on the ...
1
vote
0answers
79 views

Calculating the recursion at the Fourier domain

I would like to calculate the following recursion with mathematica $$f_n(x)=\int_{B}^{A}f_{n-1}(x-\omega)f(\omega)\mbox{d}\omega\quad\quad f_1(w):=f(w)$$ This is simply the convolution of $f$ with ...
0
votes
1answer
199 views

How to include constraints in `NMaximize`

I am trying to find maximum likelihood estimates of parameters for a fairly complicated multivariate distribution. The support of the distribution depends on its parameters so I need to include some ...
1
vote
0answers
264 views

Solve set of non-linear equations with least-squares-fitting - constrain results?

I'm trying to solve a set of functions to determine the material properties from a set of measurement values. (To set up this method I just want to fit my model with some already calculated data). My ...
3
votes
2answers
147 views

Vertex Names of Subgraph in Order of Connectivity

I extract path subgraphs $P_4$ of an undirected graph $G$. And want to list the VertexNames of the subgraphs in the same order as they are connected. Here is an example: ...
1
vote
0answers
1k views

NIntegrate: integrand has evaluated to non numerical values

I have pasted a code that has been giving me some trouble and errors when I try to compute. ERROR: "The integrand 1435.1232 E^(-6.4703566*10^6 s^2) deEntrance[s,phi]^2 has evaluated to ...
1
vote
2answers
122 views

What is the 'Mathematica-way' to test a variable transform?

Hello Mathematica experts. I would like to play around with a simple variable transformation, to test some claims about it. I wonder if there is a Mathematica-like way to do this. The specific case ...
0
votes
2answers
399 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
118 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
649 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 ...
33
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, ...
4
votes
1answer
359 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, ...
5
votes
2answers
160 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
310 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
413 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
326 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
2k 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)). ...
6
votes
2answers
337 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
141 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: ...
5
votes
1answer
135 views

FunctionInterpolation error when specifying AccuracyGoal

Bug introduced in 8 or earlier and persisting through 10.4 or later In the help page ref/message/FunctionInterpolation/ncvb, it is mentioned that one should ...
1
vote
1answer
135 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 ...

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