10
votes
2answers
253 views

Is there a method to enumerate the keys/values of System`Utilities`HashTable

Lacking from the simple API of System`Utilities`HashTable is a method to enumerate the keys/values. ...
1
vote
0answers
33 views

Shortcuts for Indentation in Text Cells?

Marking a cell's bracket and then using Alt-7 I can make it a Text cell using the formatting set forth in Default.nb or in a modification of it stored with the notebook itself (so called "private ...
6
votes
1answer
63 views

RandomPoint fails with a large enough number of points

Bug introduced in 10.2.0 and fixed in 10.3.1. RandomPoint is new in 10.2.0. I have defined a simple ellipsoidal parametric region: ...
1
vote
1answer
36 views

Limit involving DiracDelta gives zero [on hold]

Why is the following limit zero? In[147]:= Limit[DiracDelta[ϵ], ϵ -> 0] Out[147]= 0 It does not matter if the limit is taken from either sides (+/-), since ...
1
vote
0answers
29 views

Hidden assumption in Mathematica integration [duplicate]

If I do Integrate[Exp[I*omega*t],t], it gives me $\frac{1}{\omega} e^{i \omega t}$, as expected in most of the cases, except when $\omega$ is 0. Mathematica seems ...
8
votes
1answer
104 views

FilledCurve inside GraphicsComplex doesn't interpret the integers as points

Bug introduced in V9.0 or earlier and persisting through V10.3.1. Here's an example: ...
14
votes
1answer
155 views

Grid cuts my images

Bug introduced in V9.0 or earlier and persisting through V10.3.1. pic2 = ImageResize[ ImageCrop@Rasterize@Graphics@Disk[], {Automatic, 40}] ...
6
votes
1answer
651 views

FEM: user material subroutines (UMAT in ABAQUS), mechanics

Just a quick question (mainly for those who are also familiar with ABAQUS or other comparable FEM programs and non-linear modelling of mechanical behavior, e.g., plasticity). Is there any module in ...
0
votes
1answer
46 views

Force mathematica to consider variables as real [on hold]

I want to implement an optimization of the form: NMinimize[{function,{constraints:A1^2+A2^2+A3^2+A4^2 ==1}},{A1, A2, A3, A4}] where I want to tell mathematica ...
0
votes
1answer
39 views

Bilinear interpolation [on hold]

I have a matrix with n rows and m columns. I would build a two-variables function which interpolates these points (it's a bilinear interpolation problem). How can I found a two variables function ...
3
votes
1answer
49 views

How can I convert a 3D contour plot into a region for use as a custom slice in ListSliceDensityPlot3D?

The documentation for ListSliceDensityPlot3D says ListSliceDensityPlot3D[{{x1,y1,z1,f1},{x2,y2,z2,f2},…},surf] generates a ...
3
votes
1answer
71 views

Calculating products of given length of two matrices

I have the following problem to solve. Let us have two given square matrices $A$ and $B$ of the same size and a positive integer $n$. I would like to produce all products of length at most $n$ of ...
0
votes
0answers
30 views
0
votes
0answers
31 views

Problems in animating graphs and its extrema

I tested to animate 2D graph and its extrema for simple case using Mathematica. ...
3
votes
1answer
42 views

Shared variable can not be distributed again after UnsetShared

I see a weired behavior in my MM 10.3 version. Can someone reproduce it or explain what is going on? The code is easy: ...
0
votes
1answer
59 views

Discrete Fourier Transform: help on how to convert x axis in to the frequency when I have a set of data samples [duplicate]

I have a huge data set (400000 sample) and when I plot them ListLinePlot[Au4, PlotRange -> {All, All}] I used the following code to Fourier transform it ...
1
vote
1answer
53 views

Product derivative on derivative [on hold]

this is a silly question, probably. How to product derivative on derivative in Mathematica. I mean for example how to achieve this result: Just more explanation. I need this for solving task with ...
7
votes
1answer
263 views

How is LHS = RHS; … ; LHS (nontrivially) different from … ; RHS

I'm trying to understand how Mathematica thinks about the results of Set. Suppose we perform LHS = RHS. I'm focusing on when ...
0
votes
0answers
19 views

Solving a simple ODE [duplicate]

I am trying to solve $y(x)' = \sqrt{y(x)}$ with initial condition $y(0)=0$ for $x\in \mathbb{R}$. I have tried this: DSolve[{y'[x] == Sqrt[y[x]], y[0] == 0}, y[x], x] but this gives {{y[x] -> ...
0
votes
0answers
19 views

Popup window shows after kernel closed when using J/Link

A popup window always show after kernelLink.close(); And this only happen after expression evaluated as graph. Such as ...
4
votes
2answers
74 views

A simple question about replaceall and plotting

I was trying to replicate the picture produced on the following Wikipedia page: https://en.wikipedia.org/wiki/Evolute with the astroid emerging as the envelope of normals to the ellipse. I ran into ...
0
votes
0answers
47 views

Riemann Zeta function definition was expanded by Euler with an infinite product series [duplicate]

The Euler infinite product series definition for Riemann's zeta function requires that Mathematica use all prime numbers in the product series. Can anyone help me with the code that will give a ...
0
votes
0answers
32 views

Substitute arguments before evaluating variables in Block [duplicate]

Suppose I have f = x^2; mod[x_] := Module[{}, f] Then mod[3] returns x^2. Is there any way to tell Mathematica to treat the "x" inside of f as the same "x" as ...
0
votes
1answer
38 views

Plotting a function based on complicated integral

I have this function : f[Lambda_] := K Integrate[x Exp[- x^2-Lambda x] HypergeometricU[-Lambda,1/2,(x+ Lambda/2+2)^2],{x,0,Infinity}]; where ...
4
votes
0answers
39 views

How to set Ticks for an AngularGauge?

How do you set custom ticks on an AngularGauge. ...
3
votes
2answers
237 views

Rotating an Interpolating Function

I have used the following code to generate eigenfunctions of a PDE: ...
-4
votes
0answers
59 views

How can I graph this using Mathematica [closed]

How can I graph the equation $x^2+y^2\le9$ and rotate it about the x=5 axis. This should make a Torus. The problem is that when I use RevolutionPlot3D it returns a sphere. I just can't get it to ...
1
vote
0answers
34 views

Coding help on plotting two functions [on hold]

I am trying to plot two functions. Trying hard, but not able to see what is wrong in the function definitions. ...
0
votes
1answer
102 views

Plotting a Double Sum

I am attempting to plot a graph of a function that is the absolute value of the double sum of an exponential function, and I keep getting errors. Here is the code: ...
0
votes
0answers
21 views

N[variable,2] displays 6 digits [duplicate]

The following code doesn't behave as I expect. Rather than getting 2 digits upon varying r, I get the default value of 6 digits. What's up? ...
0
votes
4answers
123 views

Removing a ProgessIndicator when no longer needed

I have a progress indicator in my Mathematica notebook that I update as various calculations are performed: indicator = ProgressIndicator[Dynamic[progress]]; I ...
6
votes
1answer
76 views

PlotMarkers shadows the settings by Style

The code below gives color-varying points with explicit Style wrappers: ...
1
vote
2answers
41 views

using Map to apply 2 lists to the LCM function - help [duplicate]

I have 2 lists of numbers and I want to quickly compute the array of answers to the LCM function for the 2 lists and a 3rd static number. I tried the following ...
3
votes
1answer
68 views

Euler-Maclaurin summation

I want to compute asymptotic approximations to partial sum of harmonic series in Mathematica, using Euler-Maclaurin summation formula. ...
9
votes
1answer
120 views

Maximizing a recursive functional equation

I would like to maximize a recursive functional equation but I am struggling with setting up the problem correctly. The equation I am interested in captures the nature of a decision process over time ...
6
votes
1answer
136 views

Incorrect Left and Right Eigenvectors in Mathematica

I'm trying to find the Left and Right Eigenvectors of a pretty straightforward matrix, but Mathematica doesn't seem to be able to do it for even a 200 dimensional matrix. Background: Given an ...
1
vote
1answer
33 views

Reverse element in nested list [on hold]

Suppose I have a list as the following: list={{1,9},{7,0},{8,6}....} How can I reverse the element in such way that the output would be the following: ...
1
vote
0answers
29 views

How to simplify a ratio [on hold]

I have a ration of the form $\frac{p^2}{(p^2+1)^2}$. I can simplify it using $p^2=p^2+1-1$, and to get $\frac{p^2}{(p^2+1)^2}=\frac{1}{p^2+1}-\frac{1}{(p^2+1)^2}$. How can I create the rule to do it ...
2
votes
3answers
63 views

Difference between two Listplots [on hold]

this is a simple question, and excuse me if it's already been answered; I searched around and couldn't find anything. I have two listplots, both along the same number of x data points, but with ...
0
votes
0answers
26 views

Unstable command line startup time [on hold]

I installed Mathematica in an Ubuntu machine, and the start up time in command line is very unstable. Some times open instantly, another times get 40 seconds to open it. I'm using no interface, just ...
0
votes
0answers
73 views

How to take a count of polygons? [on hold]

I have the following polygon values: ...
1
vote
1answer
37 views

How can I change the autonumbering criterion?

In a notebook I have three cells whose format is DisplayFormulaNumbered: a=1 b=2 c=3 and in a text cell I refer to them respectively as (1) (2) (3), where (1) ...
1
vote
0answers
42 views

NDSolve memory usage

I am trying to solve numerically a system of linear ODEs with some quickly varying driving functions. The basic command is: ...
42
votes
2answers
1k views

Numerically solving Helmholtz equation in 3D for arbitrary shapes

Context While studying manifold Learning I got interested in finding the eigenvectors of the Laplacian. (also in connection to this problem of solving the heat equation) Following this and that ...
5
votes
1answer
186 views

Trace one point's coordinate values in sequentially images

I am a research student in a university. I think I need some help. I used a video camera to monitor the vibration of a plank. Then I should calculate the amplitude and frequency of the vibration ...
18
votes
6answers
830 views

Historical Exchange Rates via FinancialData

FinancialData["name"] and FinancialData["name", start] return respectively; the last known price, and the daily closing values ...
0
votes
1answer
96 views

How can we draw a stencil for discretization of PDEs?

How can we draw some multi-node (e.g. 5-node, 9-node, etc.) stencils that occur in the process of discretization of PDEs, such as the following ones? or As a matter of fact, I would like to ...
1
vote
1answer
140 views

Only perform a symbolic differentiation once

I want to define a function that involves a differentiation step that Mathematica can do easily, which might be of the form ...

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