All Questions

4
votes
0answers
31 views

Visualisation of intrinsic curvature

I know that Mathematica allows for a lot of nice visualisations, so here I am. I was thinking if one could visualise (using Mathematica) the fact that a 3d (or simpler a 2d one) Torus doesn't have ...
5
votes
0answers
62 views

Why does the documentation call functions “pure”?

Clearly, functions in mathematica are not pure functions according to the definition on Wikipedia (no side effects - basically implementabe with table lookups): ...
2
votes
0answers
25 views

Simulating Dynamic Priority Queues

I have found several examples of static priority queue implementations: there are two classes of items, with the exponential interarrival times. The service times are also exponential. The first-class ...
0
votes
0answers
21 views

Confusion/Problem with importing Packages in Mathematica

I am very new to Mathematica and managed to confuse myself completely while trying to import a package. I am supposed to use a package that I did not code myself (it definitely works though). I ...
0
votes
0answers
20 views

Does mathematica have “Realized Covariance” function?

Does mathematica have "Realized Covariance" function? I see that the function called "CovarianceFunction" may be a little close to this, but it is not so easy to see the actual "realized" property ...
1
vote
0answers
46 views

Concise way to express Table[FactorInteger[300][[n, 2]], {n, 1, Length @ FactorInteger[300]}]

I can get the exponent part of FactorInteger[300] with Table[FactorInteger[300][[n, 2]], {n, 1, Length @ FactorInteger[300]}] ...
1
vote
1answer
38 views

Mathematica integration error

Integrate[Integrate[Abs[Exp[2*Pi*I*x] + Exp[2*Pi*I*y]], {x, 0, 1}], {y, 0, 1}] yields 0 as result. This cannot be correct, ...
1
vote
1answer
37 views

Removing non-word characters in certain parts of a string

I would like to ask how I can remove non-word characters from a string, but only in certain cases. I have read this article, so I know how to get the words out of a string. My text is however a bit ...
2
votes
1answer
36 views

Exporting animated gifs; “AnimationRepetitions”->1 doesn't work

I'm trying to export a table of graphics into a gif animated file with just one repetition. Export["C:\Race.gif", t, "AnimationRepetitions" -> 1] It doesn't ...
0
votes
0answers
39 views
1
vote
0answers
33 views

How could I upload a XLS file to Cloud and then plot it?

I want to upload a file to the Wolfram Cloud and plot the list: So I use the following code to check its head at the beginning: ...
0
votes
0answers
10 views

formulate a condition that function f(x,y) must hold in order to be considered as “associative” [migrated]

Let f(x,y):{0,1}^2->{0,1} be a Boolean function. Answer the following "warm-up" questions: a. Prove or dispute: The function f can be one-to-one. b. Formulate a condition that function f(x,y) must ...
5
votes
4answers
195 views

Computing a map between two lists

What I want is a little difficult to explain. So I try to it with an example. I have 2 lists, each of which has $(n-1)^2$ elements. Each element is an integers between 0 and $n-1$, inclusive. For ...
1
vote
0answers
61 views

Finding the point of best focus for a ball lens

This is my project (simulation): A set of parallel rays goes trough a ball lens (circular lens). Because of spherical aberration, refracted rays will not meet in a single point. Find the distance ...
0
votes
0answers
35 views

Faster way to build a specific height in a thickness plane graph?

Test image can be a Plot, ParametricPlot, RegionPlot, ...
2
votes
1answer
17 views

Put/Get don't accept a string-valued expression as filename [duplicate]

I'm trying to do the following with an expression: filename=StringJoin[{"myfile", ToString[someNumber],".m"}]; expression >> filename; But mathematica ...
0
votes
0answers
56 views

Curve fitting of a list

I have list obtained using an integrals. I want to obtain an analytical formula that fits my list using curve fitting. Please suggest a simple analytical structure that fits my curve. ...
0
votes
1answer
38 views

Histogram from a list of matrices

I have a list of around 100 matrices, that looks like this ...
2
votes
2answers
124 views

Grid lines extending too far

The grid lines in the following plot extend beyond the data and, in particular, into the numbers along the axis. ...
0
votes
0answers
20 views

How to automatically Import, Name and Export multiple images? [duplicate]

Sorry for the very basic question but I'm really new to Mathematica. I have a directory(myDataDir) full of images (myImage1.tif, myImage2.tif...) I have a piece of code (let's call it ...
0
votes
1answer
55 views

Wrong Definite Integral result [on hold]

When I calculate the definite integrate of (a+bt)*cos(nt). Integrate[(a + b t) Cos[n t], {t, t1, t2}] MMA gives a correct answer: ...
0
votes
0answers
41 views

Open Mathematica in text editor displaying just the code

I need to translate some code to another language and I don't have a working copy of mathematica. All I need it to do is display the code exactly as it would in mathematica, without any of the fancy ...
2
votes
1answer
49 views

Using RegionPlot3D to make a cone under restrictions

I have to plot a cone that satisfies this statement: Use the RegionPlot3D command to draw a picture of a cone with its point at the origin. The other end of the cone is a circle with radius 5 ...
1
vote
0answers
31 views

Using real numbers gives suspicious result

In the code below when I use a real number for number 4 in the exponent in the irf function, it returns wrong result. ...
11
votes
2answers
414 views

How to wrap a plot around a circle?

Consider the code a = Table[BesselJ[i, x], {i, 0, 3}] Plot[a, {x, 0, 20}, Axes -> False] producing I'd like to transform the plot into a circle. In other ...
-1
votes
0answers
31 views

How to replace colours in an image from Wolfram Alpha [on hold]

I recently saw this post on the Wolfram Blog. I have tried doing the exact same thing on the blog but I'm not getting the same results. I'm getting this image: Instead of this: I'm also ...
-1
votes
0answers
50 views

Proof that $(1+\epsilon)^n = O(1+n\epsilon)$ [on hold]

How to prove that $(1+\epsilon)^n = O(1+n\epsilon)$ ? So far I proved the following: By the binomial, $(1+\epsilon)^n > n\epsilon$ Also $\epsilon^n$ = 0 when n-> infinity.
0
votes
0answers
60 views

Problem in Plot at start [duplicate]

The derivative can be used to calculate roots. However the same function cannot be plotted.The error is at start point of domain: ...
2
votes
1answer
30 views

Mapping also for one element (or telling it how to do so if head got changed)

Some code generates a polynomial, and has the form: expr = Plus[a[i],b[i],c[i],d[i]] I need to apply f to each term. To do ...
0
votes
0answers
37 views

Handling Accuracy and Simplifying

I have the following problem. I have a system of non-linear equations that I log-linearize around a certain point, let's call it point A, using a function that I ...
4
votes
1answer
56 views

Functional defined Ticks of LogLinearPlot does not work

version 10 $Version "10.0 for Microsoft Windows (64-bit) (June 29, 2014)" Consider three cases in LogLinearPlot's ...
9
votes
2answers
242 views

Is there an easy way to use Matteo Niccoli's perceptual color maps for 2D plots in Mathematica?

I have been using the ubiquitous Jet color palette for 2D plots for some time now, and don't really care for it. Then I came across the series of blog posts, The rainbow is dead...long live the ...
3
votes
1answer
67 views

Remove redundant parameters from equation

I have random expressions like (b1 x + b2 x)/(b3 + b4/b5 x) + Sin[b6 x] where $x$ is a variable and {b1, ..., b6} are parameters to be fitted. This expression is ...
0
votes
0answers
41 views

Is There a Reliable Way to Solve the Following Non-linear PDE Using Mathematica? [on hold]

I'm trying to solve the following non-linear PDE using Mathematica. Indeed I should write my own codes, but I didn't do it for two reasons: 1. there seems not to be any reliable way to "discretize" a ...
1
vote
1answer
64 views

handling division by zeros and line equations

today I was writing a code which takes some line equation and a circle equation,finds intersection points that are on $II$ and $III$ quadrants,draw a tangent line to circle from that point and then ...
1
vote
1answer
28 views

problem on returning value of function as a list using if

today i was writing a function for my project using mathematica that gives a line equation in form of $y=mx+b$ and a circle equation in form of $x^2+y^2=r^2$ and finds the intersection point which is ...
0
votes
0answers
42 views

Empty Graph for Absolute Function

I wanted to plot the following equation: Plot[((x/7)^2 Sqrt[(Abs[Abs[x] - 3]/(Abs[x] - 3))] + (y/ 3)^2 Sqrt[(Abs[y + 3 Sqrt[33]/7])/(y + 3 Sqrt[33]/7)] - 1) (Abs[x/2] - ((3 ...
0
votes
0answers
29 views

Series expansion of InterpolatingFunction obtained from NDSolve

I am trying to obtain a series expansion of the numerical solution of a differential equation. I encounter difficulties going beyond first-order expansions which I believe might be due to my inability ...
2
votes
3answers
87 views

Partitioning time series

I have a time series dataset I'm trying to plot by Year: ...
0
votes
1answer
40 views

Why don't these assumptions result in further simplification?

I'm trying to simplify an expression, which has a factor of $\lambda(\lambda-1)$, where $\lambda$ may be either $1$, or $0$. So I try: ...
0
votes
2answers
36 views

Why can't I import a file in the init.m file?

I would like to have some data read in every time the kernel starts, but it doesn't seem to work. Say I have a CSV file I want to have read in, for example I use: ...
5
votes
3answers
112 views

How do I display the parameter value in animate, similar to how it's done in manipulate?

When I use manipulate, there is a 'plus sign' in the top right that, if I click on, shows my parameter value. I used animate, because other posts suggested that it solved other issues I had, but now ...
13
votes
0answers
121 views

DumpsterDoofus's captivating generative art

How can I render these beautiful images that DumpsterDoofus posted?
1
vote
2answers
69 views

Changing the Ticks in LogLinearPlot for representation pH values

I need to change the ticks in the xaxis for representation pH values, but the ticks are not dispersed along the range of xaxis. Another question: why the vertical line defined with Epilog is not ...
0
votes
0answers
10 views

Changing variable value via loop [on hold]

Just a quick question, I have the following code: Do[{ Mtest = 2; Mtest = Mtest + 0.1; Print[Mtest] }, {n, 1, 5}] What I hope to do is have it loop 5 ...
2
votes
1answer
38 views

Is there a simple function identify the sign of an expression given constraints

I'm looking to find a simple function that can identify the sign of an expression given a set of constraints. I have looked around and do see that there is a few threads on this but I'm not sure I ...
1
vote
2answers
67 views

How to solve ArcSinh equation for many differents parameters?

I am totally stuck trying to solve the equation below (1/2) x Sqrt[1 + 4 a^2 x^2] + ArcSinh[2 a x]/(4 a) == d Where a and ...
3
votes
1answer
445 views

Over 30mins to generate the first eigenvector?

Is it normal for Mathematica to take over 30mins to try to compute the first eigenvector of a 100x100 matrix? The matrix is reasonably sparse - about 90% of the cells are 0s and each column sums to ...
1
vote
1answer
61 views

How to form a variable from matrix elements

I have matrix with n rows and 2 columns, say m = {{x11, y12}, {x21, y22}, ..., {xn1, yn2}. Now, I want to form three new variables for example: ...
0
votes
0answers
28 views

Pick out element from array [on hold]

I have the $3\times 3 \times 3$ array: ...

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