# All Questions

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### Learning Resources for Data Science in the Wolfram Language

I'm delivering an upcoming course on Data Science with the programming/analysis done predominantly in the Wolfram Language. I created the following table to leverage students' familiarity with Lists ...
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### Why can NSolve only solve this system of equations after trivial substitution?

The first system immediately yields {}, but the second, equivalent, system yields the solution {{k -> 4.96048, tl1 -> 1.64842, tl2 -> 2.07466}} : ...
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### What is that Root[…] inside the answer represent? [duplicate]

So I am encountering this situation, in which mathematica doesn't give me the answer, but in a form of "Root". How do I interpret this ? what is the number after the "&" represent? How should I ...
103 views

### Undirected Network and its Monte Carlo Simulation

So I have this array of points, in the form {x, {y,z}}, where x is the node number assigned when I used the locator pane to make a network, and y and z are its unitary coordinates. The graph is made ...
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### Interpolation function rejected by ParametricPlot3D

I was playing around with the bouncing ball example, and decided to make a 3d version. I decided to use ParametricPlot3D for a simple independent 3D ...
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### How to handle infeasible points in FindRoot?

I am calling FindRoot[f[x,y],{{x,xInit,xMin,xMax},{y,yInit,yMin,yMax}}] where for some points {x,y}, ...
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### Probablity weighted ReplaceAll

I'm looking for an elegant way of doing a probability weighted replacement rule, something like this ...
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### Given f[1] … f[k], k = 1, 2, 3… how do one find the general function f[n]?

If I have that ...
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Consider replacing head of List by head Association: {a -> x, b -> y, c -> z} /. List -> Association (*<|a -> x, b -> y, c -> z|>*) ...
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### Plotting and NIntegrate [on hold]

I have a problem. I try to make such a plot: function = y^(3/2)*Exp[I t y - y^2]; Plot[NIntegrate[function, {y, -∞, ∞}], {t, -20, 20}] But I have no plot - I ...
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### Operator-Input Form for Lists?

The documentation on Operator-Input Forms shows the following example which suggests that there is an alternative, convenient, operator-style, tidy technique for inputting lists. However, there is ...
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### Can NDSolve handle discountinuos data?

It is possible to numerically solve a differential equation if not-smooth data are involved? For example the following instruction return the error NDSolve::bvdisc: ...
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### Backslash commands in strings?

I discovered by playing around that Text[DisplayForm@SubscriptBox["\[Lambda]", "k"]] produces the same result as ...
95 views

### Is there a faster way to Map an Association?

Consider mapping an existing Association in a manner such as this: ...
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### Automatic substitution of fractions

I have several equations with many variables, and here and there I would like to do a variable substitution. For example, in the equation: a (b + 42 c / d) I ...
56 views

### Substitution in Mathematica [on hold]

I am new to Mathematica and hope to learn a lot here. Could you help me with the question below. Thanks! Here is the expression: ...
114 views

### Which function definition is used to evaluate an expression that matches the lefthand side of more than one definition?

In a case like this: f[a_] := a; f[{a_, b_}] := a; I'm wondering whether I should expect f[{2, 3}] to return ...
164 views

### Testing Credit Usage in Wolfram Programming Cloud

I currently have a free WPC account, which I am using for testing purposes. Amongst other things, I want to find out more about how the credit system works, in particular how many credits are used, ...
32 views

### Unique CellID in-between notebooks

Documentation says that CellID is guaranteed to be unique for a given notebook. I've noticed that CellID are fairly high numbers and although probabilistically speaking the odds of coincidence are ...
44 views

### Black line after ImageTrim

as shown in Image correlation I would like to detect the shift between a stack of images. Here are the images: and here the code: ...
94 views

### How do I exclude the vertical line plotted at a discontinuity?

Condsider function = Tan[1 x] + Tan[2 x] Plot[function, {x, 0, 1.5}] It has a strong discontinuity around 0.8. The problem is , if I want to find ...
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### How do I plot a U- form cylinder

I'm really new to Mathematica, trying to learn some things, but I need help trying to plot this kind of cylinder, a U tube like cylinder. Tried to use an example code like this, and then vary some ...
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### Solving a system of equations over a custom domain [on hold]

I'm trying to solve a system of linear equations with a large number of variables, but Mathematica is having real trouble finding solutions in a reasonable amount of time. One thing I thought would ...
34 views

### Specifying parameters for the Ticks option [on hold]

I'm trying to use Ticks option with ListLinePlot to put ticks at 1, 2, 3, 4, 5, 6, and 7 on the x-axis the points and at 1, 2, ...
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### How Construct Clopen-Compact Bitopological Spaces? [migrated]

Dear all who love general topology, In general topology we know the notion of clopen-compact spaces (introduced by A. Sostak): a topological space $(X,\tau)$ is called clopen-compact if every clopen ...
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### How to get a list of all expressions in a notebook matching a certain pattern?

Suppose I have a Mathematica notebook saved to a certain location on disk. Given a pattern I need to get the list of all expressions matching this pattern that appear in input, output or print cells ...
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### Improving the speed of evaluating Table with nested functions

I am a Mathematica novice working with a stack of 1024 x 1024 WatershedComponents (or MorphologicalComponents) label matrices ...
73 views

### Inconsistency of output format in Eigenvalue

I am bothered by the output format of the last two elements of efre. Is there a way to make these two look like the same format as the first two in ...
166 views

### A Case of DeleteCases for WeatherData

I am trying to use ListVectorPlot in combination with WeatherData and CountryData to show ...
108 views

### Providing a color function for ListPointPlot3D

Is there a way to write ListPointPlot3D expression, so when given a list of points, the the color of the points plotted is a function of the index/element number of ...
135 views

### Converting a nested for loop from MATLAB

In MATLAB I have the following series of nested for loops that update a matrix. (It's not my code, but someone else's that I'm trying to replicate - I don't know ...
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### eccentric anomaly expansion equation

I try to use this simple algorithm (paper) to calculate the Eccentric Anomaly expansion: ...
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### Partial Differential Equation in Parallel

is there any native way to implement multi-core parallel solving of PDE in Wolfram Mathematica? WM 10 now supports Finite Elements Method, but it is actually useless without parallelization. Usually ...
137 views

### Zero-order interpolation not going fully around

Connected to this question, I want to do a zero-order interpolation of a bunch of datapoints which is periodic. The code I use is as follows: ...
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### TrueQ returning False on true statement

Why does TrueQ return False on the following? TrueQ[Log[2]/Log[8] == 1/3] (* False *) ...
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### How to correctly use PatternTest (?) [duplicate]

This works fine: {3, -5, 2, 7, -6, 3} /. x_ /; x < 0 :> 0 (*{3, 0, 2, 7, 0, 3}*) and this works fine: ...
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### Utility information using FindGeoLocation in Ver.10

It is possible for some commuters to track the location of their bus, train or tram through a personalised GPS tracking device (e.g.see ...
219 views

### How can I mend this broken heart?

Try to evaluate the following code: ...
129 views

### How to slice TimeSeries data?

When retrieving curated data, v10 now returns TimeSeries objects. For example, ...
127 views

### Geographic background containing both outlines and contours: how?

I would like to create a map which will show lakes and rivers together with elevation contours and contour labels. What is the simplest way to do this with ...
61 views

### how to write TableForm expression into file?

Now I have a list stored in data as follows data = {{"Ca", 1, 1, 1}, {"Ca", 2, 2, 2}, {"Ca", 3, 3, 3}} the ...
37 views

### Finding Roots of Non-linear Systems: Rescaling polynomials

I'm trying to get all isolated finite equilibria of a moderate multi-dimensional non-linear system of equations. Particularly I have 9 independent variables and third order at most. It turns out that, ...