5
votes
3answers
123 views

Elegant way to drop rest of a string at the occurence of a character

For example, I have a string "ahfiehfke$jfwfjejf0". Is there an elegant way to drop all characters after "$"? I know loop ...
2
votes
2answers
76 views

How to make such a $N(0,1)$ sketch for standard normal Z?

My attempt: Plot[PDF[NormalDistribution[], x], {x, -4, 4} , AxesLabel -> {None, "Z"}]
1
vote
0answers
35 views

Module does not evaluate the same way as without [closed]

I have a module as follows: ...
1
vote
1answer
287 views

Create a function with Dt[x] as a variable

I have a function (for example F[x_]:=Cos[x]). I want to define a function like Fdot[x_,xdot_]:=Dt[F[x]] where xdot represents Dt[x]. For example, to define Fdot one might naivley try ...
3
votes
1answer
96 views

How can I draw a histogram from a nested list?

I have a nested list of the form list= {{1,1,1},{1,2,3},{1,1,1}} How can I plot a histogram that tells me how often each number pattern appears in my list? For ...
1
vote
0answers
74 views

Tracking solutions over a Brillouin zone

Thanks to @bbgodfrey I have a function that finds the two solutions to a set of equations bounded by a hexagonal region (corresponding to the Brillouin zone). It takes the angle ...
7
votes
2answers
391 views

How to read complicated result from Reduce?

How can I read this Reduce output from Mathematica that I got from solving an inequality? I do not perfectly know when one case in this case analysis is over and ...
1
vote
0answers
150 views

Bad rendering of rotated text in 3D graphics in notebooks

Why is my rotated text so badly rendered in 3D graphics in notebooks (the exported pdf are OK). It happens for me with v9 or v10.1.0 and OSX (10.9.5). Notice that the rendering is good in 2D ...
7
votes
1answer
198 views

How would I use Map on a Dataset column?

I am somewhat new to functional programming. To improve the performance of a package, I would like to re-write a package in a functional style. I have the following ...
1
vote
2answers
89 views

How to contour shade two specified contours?

I want to have contour shading between two contours specified by two equations like below, ...
0
votes
1answer
114 views

Replace instanced variables within module-return functions for dynamic Tooltip

Currently I am stuck with the issue of renaming an instanced variable like r1$38655 to a global one. The function is created within a "localizeAll" Module. Here's ...
1
vote
1answer
263 views

RSolve with integrations

I want to solve this question with Mathematica. $$T_0(t)=c(t),\quad T_n(t)=a\int_0^t T_{n-1}(s)\, \mathrm{d}s+b(t).$$ Is it possible to solve $T_n(t)$ with ...
6
votes
1answer
158 views

Easy FindMaximum returns a wrong answer

FindMaximum in region is a new function in mma10,but when I tried the following example: ...
2
votes
0answers
48 views

Custom graph distribution

I am working with random graphs a lot. It's quite easy to describe random graph using, adjacency matrix or just a list of edges. However I am thinking that I might benefit from describing random ...
1
vote
2answers
99 views

How to show system busy during Dynamic with SynchronousUpdating -> False?

For long running evaluations in Dynamic it is recommended that SynchronousUpdating -> False be used to prevent time-out. ...
4
votes
2answers
1k views

How to draw confidence ellipse from a covariance matrix?

I am studying a two-dimensional dataset, whose mean vector and covariance matrix are the following: ...
0
votes
0answers
102 views

Volume by NIntegrate gives zero

I want to Integrate the following expressions for different p < n and 2 < n with p and n both natural numbers: ...
0
votes
1answer
94 views

solving quadratic and linear congruences with different modulus

We are able to solve the quadratic congruences $C^2 + Q^4 - 2\equiv mod 3072$ and $C - Q^2 - 2046\equiv mod 3072$ by entering ...
-1
votes
1answer
95 views

How to make sure input is an ODE

I'm having trouble wrapping my head around why this isn't an ordinary differential equation. ...
0
votes
1answer
89 views

Why does my function return an expression rather than a number? [closed]

I feel like I'm going insane. I have a function $f(x)=e^{-x^2}$ which I need to evaluate using forward, backward and central first order finite differences with intervals ...
10
votes
2answers
221 views

Comparing natural language strings

I have a large spreadsheet with thousands of rows/columns of text. Some are saying essentially the same thing but in different ways. When you enter a natural language question Wolfram Alpha makes a ...
0
votes
2answers
110 views

Control legend size when autoLegend is used with LinTicks [closed]

It looks simple, but I'm been trying to solve this issue for days, but no luck yet. So, here I used LinTicks, as customized option and another graphic option. Here ...
0
votes
1answer
89 views

usage of random numbers in recursive loop

I am trying to evalute two functions using iterative process as below ...
2
votes
1answer
142 views

how to calculate the covariance of sample central moments

$\bar{x}= \sum_{i=1} ^{n} \frac{1}{n}x_{i}$ $m_1=\sum _{i=1} ^{n} \frac{1}{n} (x_{i}-\bar{x})$ $m_2=\sum _{i=1} ^{n} \frac{1}{n} (x_{i}-\bar{x})^2 $ $m_3=\sum _{i=1} ^{n} ...
0
votes
1answer
251 views

How To Use D[ ] to Define a System of PDEs

We have two variables $u_{1}$ and $u_{2}$ which are functions of $x,t$. That is, $u_{1}=u_{1}(x,t)$ and $u_{2}=u_{2}(x,t)$. Consider the the system of partial differential equations $$\frac{\partial ...
1
vote
1answer
42 views

Out labels looks strange after turning on magnification

As everything in Mathematica looks too small to me, so I turned on magnification when I am working. It looks good on windows: However, the Out tag is dislocated ...
2
votes
0answers
52 views

Import names into notebook namespace [duplicate]

I have function that at some point has list of strings (e.g. {"apple","pear"}) and I want to declare (initialize) those variables in notebook namespace to default ...
4
votes
1answer
156 views

Arrowheads in VectorStyle and StreamStyle doesn't work properly in VectorPlot and StreamPlot, respectively. A bug?

I'm using Mathematica 10.0.2 for Mac. Arrowheads given in VectorStyle for VectorPlot ...
6
votes
1answer
125 views

Graphics3D and Bit Depth of Rendering

A year or so ago, I sent this question to WRI (nb- a former employer of mine) and, as happens with bug-reports-that-arent-bug-reports, it was swallowed into the black hole that is Chambanna. So- I ...
1
vote
1answer
102 views

Finding adjacency matrix of a Mathematica's in-built graph? [closed]

I want to get the adjacency matrix of an in-built graph, say the dodecahedral graph. Naively using AdjacencyMatrix[Dodecahedral] doesn't give it to me. Any ...
4
votes
0answers
137 views

Possible Mathematica Bug? Blank Screen

I'm a student using Mathematica on a 2012 macbook pro with OS X Yosemite. Mathematica was running fine on my computer for a long time - one day, seemingly randomly, a blank screen started appearing ...
1
vote
0answers
40 views

Does “FiniteRingData” or something like that exists?

I want to find a function like FiniteGroupData but for finite rings. Does something like that exists?
2
votes
4answers
128 views

Pairs of data to Classify[]

Suppose I had the following data a={1,2,3,4,5} How would I turn this into b={{1,2,3}->4,{2,3,4}->5} That is, ...
1
vote
1answer
2k views

Add assumptions to Solve command

I want Mathematica to solve the following by assuming the part within the Log function, which is ...
5
votes
2answers
137 views

How can I run a list of Tasks serially?

I have a list of ScheduledTask's to run in sequence one at a time. How can I set these to run in order so that the next one starts automatically after the previous one finishes?
3
votes
0answers
60 views

Why does the debugger not stop when a message is generated?

I am on version 10.1. I have enabled the debugger and I have checked the box in front of "Break at Messages" in the Debugger Tools Window. However most the time the debugger does not stop when a ...
19
votes
1answer
721 views

Difference between Fitting Algorithms

I am new to Mathematica, and I don´t quite understand, what the difference between the fitting algorithms Fit, FindFit, ...
8
votes
1answer
893 views

Animated Wave propagation using split operator method

Here is the state of the art: By solving the time-dependent Schrödinger equation, one obtains that the propagated wave function after time step $\Delta t$ can be calculated by applying the ...
2
votes
1answer
128 views

Package editor interface

Is there a way to get rid of the unused space on the left of the package editor? What is it's purpose if I configured Mathematica to not show In and ...
1
vote
1answer
230 views

Plot a numerical integration as a function of a variable

Suppose we have a function that is hard to evaluate analytically but a numerical estimate suffices. For example consider the $f(x,\Lambda) = \Lambda\cdot \sin(x)$ where $\Lambda$ is some parameter I ...
7
votes
7answers
453 views

Generate a list

Given the list o = {xmin, xmax, ymin, ymax}; how can I generate the following list? ...
2
votes
2answers
136 views

How to speed up a system simulation?

I need to simulate a series of nonlinear (and linear) with thousands of state variables. Here is a simple linear example ...
4
votes
3answers
195 views

Best way to represent a complex time schedule?

What would be the best way to represent a complex schedule in Mathematica ? For example a representation of the plain words schedule: "From Monday to Friday, from 8 am to 12pm and from 1pm to 4pm", ...
7
votes
0answers
261 views

How to generate a random flow graph?

A flow graph is a rooted directed graph that the root reaches all other vertices. I need to generate a random flow graph in Mathematica. My idea is to use ...
1
vote
2answers
55 views

Subsituting expressions for expressions

I'm trying to define functions using other functions, like so: f[a_, b_] := a/b; a[c_] := c; b[d_] := d; Now what I want to be able to do is two things: ...
0
votes
1answer
356 views

How can I use nonlinear model fit with multiple variables? [closed]

I have a data set with four entries. the first three entries correspond to variables in the fit x,y, & z. The fourth entry corresponds to the function value. I am trying to fit this data to a rate ...
3
votes
0answers
78 views

How to speed up solution of system of recurrence equations

I was wondering how I can improve the speed on this method for solving a particular system of coupled recurrence equations. The system is $$ \begin{align*} &V(m)=\alpha + \beta V(m+1)+\beta ...
2
votes
1answer
228 views

How do I download and export data from many weather stations?

I tried this code, which downloads data from several weather stations. ...
-1
votes
1answer
75 views

Factor out certain terms using Modulus but Mathematica requires that the modulus be an integer [closed]

Mathematica demands that the modulus be an integer. How do I work my way around this?
5
votes
1answer
481 views

How to plot the solution of a Partial Differential Equation?

My attempt. I need to solve numerically the Complex Ginzburg-Laudau Equation (CGLE): $$ \frac{\partial A}{\partial t}=\epsilon A-(1+i\beta)|A|^2A+(1+i\alpha)\nabla^2A $$ I'm using a uniform initial ...

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