19
votes
3answers
914 views

How to extract the edge from a set of points

I have an accumulation of points representing a body as you can see in the image below. From this data I want to generate a list of points or a curve, which is the envelope. The first idea was a ...
2
votes
0answers
57 views

Equation involving hypergeometric functions

I want to solve this equation but nor NSolve nor Solve are able to do this. ...
0
votes
1answer
106 views

Plotting error table in 3D

I have an error table which includes three parameters(error, epsilon and step size) and the matrix is not square. Now, I want to plot my data in 3D, but didn't manage to do it. My table is as follows ...
5
votes
2answers
184 views

Forcing Mathematica to typeset parentheses

I use the definitions from this post to typeset formulas in lecture slides. This is my function definition: ...
1
vote
0answers
51 views

Panel size undesired behaviour

This is next question from the series: better avoid Panel if you care about details. previous about FrameMargins In the ...
0
votes
0answers
46 views

How to obtain all minima? [duplicate]

If you Solve an equation, you obtain all solutions. But If you NMinimize a function, you only get one minimum. The question ...
1
vote
1answer
241 views

FindFit::nrlnum What am I doing wrong?

I have a model called qobs: ...
-2
votes
2answers
450 views

How do we solve third order nonlinear differential equation f’’’+ff’-f’2-Re2 f’=0

How do we solve third order nonlinear differential equation f’’’+ff’-f’2-Re2 f’=0 f(0)=0,f'(0)=1,f(Infinity)=0 From the OP's comment: ...
2
votes
2answers
327 views

Drawing tubes with a While loop

I'm trying to make a plot with many objects in it using a While loop. Something like the following: ...
4
votes
1answer
150 views

How to differentiate between formatted and unformatted strings?

StringQ returns True both for unformatted and internally formatted strings. To get True only for unformatted ones I have thought up the following function stringQ. Please, can you point out ...
8
votes
1answer
395 views

How to import a large (~50Mb) json file in mathematica

I am trying to import a 46Mb json file into mathematica (which by the way I exported using mathematica) but its failing with the following messages: ...
2
votes
1answer
1k views

Solving Heat equation [closed]

I want to compute the exact solution of the heat equation but I got an error. u(x,t) (equation of transmition of heat) is the solution of this differential equation: $$du/dt - \alpha d^2u/dx^2 = 0$$ ...
0
votes
1answer
226 views

Specific entry of inverse of large matrix

Given a large (say 10x10) sparse Hermitian matrix with symbolic entries, I need four specific entries of the inverse matrix. It seems wasteful to me to compute 100 entries of which I only need a few ...
0
votes
1answer
359 views

Area of a convex polygon with a set of points [duplicate]

I have a set of points Pts[a_,b_,c_]:={{a, b}, {b, a}, {c, a}, {a, c}, {b, c}, {c, b}} which define a convex polygon and I would like to find its area. There is ...
3
votes
0answers
73 views

LibraryLink parallel performance

I'm trying to use a LibraryLink function in parallel. It is an embarrassingly parallel problem, so that no dependency between those parallel tasks. However I can only get the parallel efficiency about ...
0
votes
1answer
153 views

Making an animation which displays a rotating object [closed]

I want to rotate the geometry obtained whith the input: movil = ExampleData[{"Geometry3D", "SpaceShuttle"}] But it shows an error message : Graphics is not a ...
5
votes
5answers
471 views

How to order legend in Show?

I've asked this question in Wolfram community and have not received a response. I am wondering why when I use Show to combine 6 plots, the plot legend does not ...
3
votes
2answers
188 views

Finding similar expressions in list

I have a function that returns to me lists of expressions, like: ...
0
votes
2answers
136 views

How to do symbolic definite integral without copy and paste the intermediate results?

I am do a symbolic definite integral, I am doing it like this: Integrate[1/Sqrt[(ϵ + u)^2 + Δ^2], ϵ] // FullSimplify It gives an output: ...
4
votes
1answer
203 views

Permanently set options such as metric units for W|A queries

Mathematica lets me be so lazy that I don't even have to switch to a browser to check the weather report: The only problem is that it will automatically display the temperature and wind speed in ...
0
votes
2answers
89 views

ToExpression an array

I have a .dat file. I would like to convert a big array of strings(that's what I havein the .dat file) into an array of numbers, for example ...
1
vote
0answers
73 views

Controlling output of graphics, the role of “;” and code structure/formatting

";" is described under Compound Expression as a delimiter, such that only the output of the last item in the compund expression is given. Situation: 1/ Print[] produces output whether followed by ...
2
votes
1answer
183 views

Importing web page data

I tried importing a webpage using Import: ...
1
vote
2answers
203 views

Mathematica can't minimize a function

Mathematica seems not to be able to minimize this univariate function over integer arguments, $r>2, r \in \mathbb{Z}$. ...
1
vote
2answers
271 views

How can I separate two parts of power of Exponential functions?

How can I separate two parts of power of exponential functions in Mathematica? I have an expression similar to this one: a*b*Exp[u+v]+c*Exp[u] I want to set ...
1
vote
1answer
85 views

Reading Options from DateListPlots with legends

Normally I can recover the options used on a DateListPlot easily with Options[]. However if one of the options said a Legend should be attached, it appears all the options are then unreadable. For ...
1
vote
1answer
70 views

Write memory usage to file in script

Is there a way to write the MemoryInUse into a file once a minute? In this Debugging memory leaks question there is a neat dynamic diagram showing the MemoryInUse over time. My problem is that I run ...
1
vote
3answers
138 views

Area enclosed by two functions

i want to calculate the area percentage of a function in a certain regime above a constant threshold. For example: f[x] = sin[x] x² from 0 to 2 with a threshold ...
0
votes
0answers
36 views

Output of the comand Put

I have a do loop in which I "Put" a ListPlot of a list in every iteration by doing Put[ListPlot[list],"file"] While the process is running and is still not ...
3
votes
2answers
788 views

Mathematica won't simplify the expression with obvious common factor of a fraction

I have an expression obtain from an integral, which is: Integrate[ϵ^2/Sqrt[(ϵ - u)^2 + Δ^2], ϵ] // FullSimplify The denominator and numerator of the result have ...
0
votes
1answer
127 views

Populating an array with outputs of a function [closed]

I have searched, but didn't find much help on my issue. I have an optical physics problem that I'm working on .. ...
2
votes
0answers
62 views

Maintaining postfix convention for directives in notebooks

It seems to be a fairly common convention to write certain 'meta' functions in postfix form like f[x] // Simplify to keep the the mathematical content at the ...
5
votes
2answers
419 views

FrameTicks and Ticks on Axes in Same Plot

I have a plot where I would like ticks shown on both the axes and the frame, with them labeled separately. I have custom labels for the frame and want the horizontal axis labeled with ticks ...
0
votes
1answer
245 views

Revolve A Function Around the Y axis? [duplicate]

I am seeking to revolve the are between the functions function $d(x) = Exp(x)$ and $e(x) = 4 - x^2$ around the line $x = 2$. I am using RevolutionPlot3D, so I ...
6
votes
4answers
179 views

How to select only NotebookObjects that are referring to ordinary notebooks? (not palettes etc.)

There is of course function Notebooks[] But, unfortunatelly it hasn't got useful options in this context. My question is how to pick ...
3
votes
1answer
247 views

Combine two DateListPlots and retain a time axis

I am trying to combine two DateListPlots to produce a single chart with 2 y-axis. There is an example here with regular Plots and I have tried to adapt it for time based data ...
7
votes
1answer
291 views

Returning a value from a Module

In the following simple example MyMod := Module[{i}, Do[ Return[1], {i, 3} ]; Print["test"] ] I expected the module to exit on ...
0
votes
1answer
122 views

NDSolve in exact points - nonlinear equation (Degrees and Radians confusion)

I found solutions of two nonlinear equations, but I have three small questions. First I am in confusion because of initial value. The system is mechanical and unknown ϕ is an angle, which I set to ...
2
votes
1answer
68 views

Is It Possible To Replicate Tab Stop Behaviour (or Even PageFooter Behaviour but in Regular Cell)

I am trying to insert a (text) cell into a notebook that replicates the behaviour of tab stops in MS Word, for example. Put differently, I have two strings and I want the one string to align on the ...
4
votes
1answer
201 views

Sample of the random times at which the random walk crosses the boundary

I defined a security boundary for a random walk: ...
0
votes
1answer
144 views

I integrate a real function, I want a real result [closed]

I want to count some integral in Mathematica (actually, check that this integral is zero...) I arrive to an answer which has a zero real part but has some imaginary part! Why? This could be a mistake ...
2
votes
1answer
103 views

nonlinearnodelfit with a matrix as weights

I have to fit a non linear model to my data and I am trying to use nonlinearmodelfit. The problem is that I have systematic errors, so the ...
8
votes
6answers
703 views

Alternating sum

A frog is at the bottom of a 30 metre well. Each day it climbs 5 metres up the side, but it then slips back 3 metres each night. How long does it take to reach the top of the well? Is there an easier ...
7
votes
1answer
377 views

Exporting EPS figures with dashing from ListPlot

I am having difficulties exporting EPS figures. If I use the LineLegend option to create a dashed or a dot-dashed line, it seems ok in Mathematica 9.0 e.g.: But the problem came out when the ...
0
votes
1answer
87 views

How to get diagonal matrix D from matrix multiplication of $s^{-1}$, P, and S

I am multiplying three matrices that should give me a diagonal matrix but instead of zeros for the other entries I get very small numbers. Can someone explain what is going on here and how I can fix ...
3
votes
4answers
278 views

Base 2 Tick Labels for ListLogLogPlot

I am using ListLogLogPlot and would like to express the x-axis tick labels in powers of 2 instead of the default powers of 10. Does anybody have experience with ...
2
votes
2answers
171 views

list of vectors with prescribed sum

Let $a\in\mathbb{N}^n$ and $k\in\mathbb{N}\!=\!\{0,1,2,\ldots\}$. How can I efficiently generate the list $$\{(a_1,\ldots,a_k); a_1,\ldots,a_k\!\in\!\mathbb{N}^n\!\setminus\!\{0\}, ...
3
votes
2answers
326 views

Map of Swedish regions?

There have been some questions dealing with how to draw individual US states since such data doesn't come with Mathematica through its CountryData which offers ...
0
votes
1answer
720 views

Plot not working

I am trying to generate a plot for S2[w]. My code is below ...
10
votes
1answer
237 views

Why does the order of arguments in Show influence the result?

I am wondering why there is a difference in the results from evaluating the two expressions, which differ only in the order of the arguments given to Show. When I ...

15 30 50 per page