1
vote
3answers
135 views

finding an argument of a complex number

What is the simplest way to find the argument of the following function? ((1 - E^((I π (1 - α))/(β - α)) z)/(1 - E^(-((I π (1 - α))/(β - α))) z)) as I tried the ...
1
vote
1answer
137 views

Another MoebiusMu question

When I evaluate the Mertens function to infinity: NSum[MoebiusMu[k], {k, 1, \[Infinity]}] I get -1, but I expected to get -2. I wanted to modify the ...
0
votes
4answers
639 views

How can I make a Plot over a discrete set of domain points?

I want to plot the function $y=2^x$ at the $x$-values given by Table[Prime[n], {n,20}] How should I write the plot function? Like so? ...
14
votes
3answers
586 views

How can I create a 3D FilledCurve object?

FilledCurve can create a 2D graphics object; for example: ...
15
votes
2answers
249 views

What are Root objects with multiple polynomials?

In Mathematica 9 a new flavor of Root object with multiple polynomials was introduced. For example, ...
3
votes
4answers
334 views

another way to do this mapping of a two argument function

Sorry, I'm just starting to learn mathematica. I have the following two-argument function: h[{x_, y_}] := x ^ y When I do the following: ...
4
votes
4answers
432 views

Remove linear trend from data

I have a large data set with 150k lines and two data columns. I noticed that there is a linear trend, which I want to remove. So, I do the following: first fit with a linear model ...
4
votes
2answers
374 views

Linear regression in a chosen range of points

Hi I'm absolutely newbie in Mathematica and have following problem: My list looks like {{50, 0.75}, {51, 0.76}, ..., and I want to choose a range out of my ...
2
votes
2answers
245 views

Why do Plot and ListPlot use the last PlotStyle when only one thing is plotted?

When a list of PlotStyles is given, ListPlot behaves as expected when there are multiple things to plot: ...
3
votes
1answer
315 views

on RegionPlot3D and ContourPlot3D

First I have ...
4
votes
1answer
113 views

RSolve gives a Context::ssle error

I want to solve the following recurrence equation RSolve[{(k + 2) c[k + 2] q^(k + 1) - c[k] == 0}, c[k], k] During calculation in Mathematica I get this ...
5
votes
0answers
83 views

ShowSelection color

The color of a selection is controlled by the operating system. E.g., enter the following code in separate cells. ...
9
votes
1answer
131 views

Is it possible to make v9 ignore case when completing names?

In v8, I could type, say, fulls or texf to get FullSimplify or ...
8
votes
0answers
462 views

Numerically solve 2nd order differential equation with singularity

Consider a second order differential equation with a potential that diverges at some generic value in the variable. For example: $$-y^{\prime\prime}(s)+\frac1{\mathrm{cn}{(s\mid k^2)}}y(s)=0$$ where ...
1
vote
1answer
138 views

Conditionals slower than operators?

I want to make my application faster. I tried to replace an If condition with operators. The If condition is ...
1
vote
1answer
209 views

Mismatch between Axes -> True and Frame ->True

Using Axes -> True of the following........ ...
15
votes
6answers
1k views

How to find major color in a picture?

I want to find the major color (the color which appears most often) in a picture and do some analysis later. For example, if I have this picture: What I want to do is find out that gray, red, ...
1
vote
1answer
182 views

Output precision

I've solved some equations using FindRoot and then computed some values. Now when I print the output, I only get a certain precision {{0.01, 496.983, 61.3147, ...
10
votes
1answer
129 views

How do I expand StirlingS2[n, 10] in terms of elementary functions?

I know that it is possible to expand StirlingS2[n, 10] in terms of elementary functions of n. I tried ...
0
votes
1answer
138 views

Outputting a set of graphics 3D objects with positions defined by one array and colors by another? [duplicate]

I have a set of 2- or 3-space coordinates in an array, $(v_1,...,v_N)$, and an array of RGB color values (outputs from ImageValue[]) for each coordinate, $(c_1,...,c_N)$. How can I output a ...
3
votes
1answer
819 views

Detection of horizontal lines in an image

Ok I'm trying to detect horizontal lines in an image. But the problem is that the line is quite obscure. So I'm not sure if it is even possible to extract that. I tried many different filters, but ...
2
votes
0answers
109 views

Prevent Suppression of Superscript 1 in Print

I'm trying to print Christoffel symbols of the second kind for a surface in $\mathbb R^3$. I currently am using something along the lines of ...
3
votes
1answer
203 views

What causes strange line artifacts to appear in plots with certain PlotRanges?

I have seen this strange plotting artifact occur before and I was able to make it go away by changing the PlotRange. However, this time I need the prescribed PlotRange to be what I define and I get a ...
5
votes
3answers
569 views

Solve for the intersection point of 3 surfaces

Basically, I have three 2-torus (tilted) in 3-dimensional Euclidean space. They are expressed by parametric equations: ...
4
votes
2answers
279 views

Why do I get empty graph when adding 'Abs' function?

Can someone be so nice to provide some help for this particular situation? I try to plot a graph of a derivative which contains modulus. Without it the graph is drawn correctly: But when I wrap the ...
9
votes
2answers
397 views

InverseSeries of multiple variables and multiple equations

CONTEXT Let us consider a bit of the Universe in which we draw spheres (see a high resolution image here). Astronomers have shown that the density within these spheres could be predicted quite ...
1
vote
0answers
247 views

CharacterEncoding failed when Import or Export as pdf

folowing is the content my test nb File: pdfTest.nb, contain some chinese characters: SampleCode1:pdf输入不正常。 After Save as or Export, pdf file looks well for the ...
11
votes
4answers
358 views

“Strange” behavior of Rule

According to the Help lhs->rhs evaluates rhs immediately. How to understand the output of the following code? ClearAll@x; {1, 3.5} /. x_?IntegerQ -> {x} ...
-1
votes
1answer
132 views

Creating a number station [closed]

This is a question about manipulating sound (wav files). The goal is to produce something that sounds like a number station broadcast, see e.g., 4:00 in http://www.youtube.com/watch?v=EdnoAJ7KoFE It ...
19
votes
3answers
403 views

How to flush machine underflows to zero and prevent conversion to arbitrary precision?

I'm working on some pretty intense computation in Mathematica; when my code started running slowly, I tracked the source of the problem to Exp[]. I need to ...
12
votes
4answers
882 views

Evaluation of a triple sum does not finish in reasonable time

I'm trying to compute the following triple sum, but no result is produced within a reasonable amount of time. What to do? ...
5
votes
1answer
133 views
4
votes
2answers
1k views

How to define a polynomial/function from an array of coefficients?

I have the coefficients of my desired polynomial in an array CoefArr (I'm new to mathematica, so I think of everything as arrays, it is actually a list I believe) starting with the constant at index ...
2
votes
2answers
106 views

Putting a matrix inside function

I want to fit a function to some data and inside the function there's a list here's my data ...
5
votes
2answers
926 views

Equivalent of MATLAB's “hold on” function

I'm making an animation where the number of iterations is known. I tried using Dynamic, as I prefer updating in real time over generating data before plotting. I ...
9
votes
2answers
294 views

Drawing Cylindrical Segment with Graphics3D

For a visualization I need a combination of 3 Cylindrical segments to visualize the incident, reflected and refracted beam of light at a surface. I got as far as the following code. ...
4
votes
1answer
141 views

Why is this code in functional style is slower than procedural style?

I know that in Mathematica a functional programming style is often more efficient than procedural style programming using For loops. But the code shown below seems ...
5
votes
4answers
476 views

How can I return the color at a coordinate in an image?

I have an imported and cropped image: TestPicture = Import["filepath.jpg"]; TestPictureCropped = ImageCrop[TestPicture, Min[ImageDimensions[TestPicture]]]; How ...
1
vote
2answers
91 views

Why will my plot not generate my entire plot?

I am trying to plot a sum of multiple HeavisidePi functions. A typical example would be something like this: ...
3
votes
1answer
115 views

How do I access the binary matrix underlying an EdgeDetect output?

Applying EdgeDetect to an image generates a black and white edge-detected image, which I suspect corresponds to an underlying binary matrix. How can I access this ...
-1
votes
2answers
455 views

How can I define a function which is the sum of other functions?

I have a function which is summation of another function over different i,j iterators. U[r] = Sum[V[r, i, j], {i, 1, 5}, {j, 6, 10}] and ...
0
votes
2answers
561 views

Finding max, min, and closest root of two dimensional data

I have some data that is two dimensional (traditional (x, y) format) as so: var = {{x1, y1}, {x2, y2}, {x3, y3}} I would like to search through that large list ...
10
votes
6answers
829 views

Multiplying two dimensional data by a constant

I have a list of lists of the form: {{1, 2}, {2, 4}, {2, 8}} But I want to multiply only the second dimension of that data by a constant. I know I could do this ...
37
votes
1answer
955 views

How to compare power towers in Mathematica?

First I tried it directly, but it overflowed: ...
1
vote
0answers
56 views

Decimal representations of analytic values in an expansion

I have a solution to an ODE (which I call sol), which I would like to expand in terms of Log[1+x] around x=-1. I thought that: ...
4
votes
1answer
121 views

Can I customize In[] and Out[] headers?

Can I customize the In[] and Out[] headers? I'd like to add $UserName, ...
2
votes
1answer
88 views

How to make a notebook not savable?

How to make a particular notebook not savable? Optionally, how to do this by evaluating a command in the notebook?
1
vote
1answer
456 views

Dynamically labeling a family of curves [duplicate]

I have created some simple code which generates a plot. This plot contains a family of curves created by changing a single parameter "k". I use the Table function within the Show function to iterate ...
1
vote
2answers
2k views

Font size in PlotLegends, using Table to generate the list in the legend

I am currently trying to get to graph with several functions as below. My problem is that I cannot change the font size in the legend (authomatically generated numbers by "Table" function). This code ...
9
votes
1answer
492 views

Why can't I change the value of MaxRecursion in NIntegrate when integrating BesselJ?

I am trying to evaluate this integral numerically $$ \int_0^{\infty } J_0(q R) \tanh(q) \, \mathrm{d}q $$ for large values of $R$. This makes the integrand oscillate more quickly and Mathematica ...

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