5.39 Tuesday, April 5, 2016

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Top new questions this week: 
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[Rounding the Corners of a Shape] http://mathematica.stackexchange.com/questions/111479/rounding-the-corners-of-a-shape

I was wondering whether there is an option in Mathematica that enables me to smooth the corners of a shape. The example I want to start with is the pentagon.

This can be crudely specified as

...

- asked by Mr S 100 (23 votes), answered by MarcoB (21 votes)

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[Writing functions with "Method" options] http://mathematica.stackexchange.com/questions/111666/writing-functions-with-method-options

I’d like to implement several behaviors for a particular function using a Method option added to the function definition:

Options[saveData] = {Method -> "Addition"}; 
saveData[vars_, opts :  ...

- asked by dionys (14 votes), answered by Shutao TANG (7 votes)

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[Interpretation of the result of ?@] http://mathematica.stackexchange.com/questions/111394/interpretation-of-the-result-of

This might be a very trivial question but as a beginner, I don’t know the answer. I was exploring ? and after running a cell containing ?@, I got an interesting result:

However, I’m not sure about ...

- asked by MathX (13 votes), answered by m_goldberg (15 votes)

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[Ticks in v10 - a bug or undocumented change] http://mathematica.stackexchange.com/questions/111663/ticks-in-v10-a-bug-or-undocumented-change

Bug introduced in 10.0 and fixed in 10.4

In this post @Heike provides this code:

ticksfun[xmin_, xmax_] := 
 Table[{10^i, Superscript[10, i]}, {i, Floor[Log10[xmin]], 
   Ceiling[Log10[xmax]]}]

...

- asked by leosenko (12 votes), answered by rcollyer (8 votes)

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[Why is an empty list not tested by VectorQ?] http://mathematica.stackexchange.com/questions/111438/why-is-an-empty-list-not-tested-by-vectorq

I am a bit amazed by this behavior of VectorQ[ expr, test ]: 
 
VectorQ[ {}, NumberQ ] 
 
  True

It seems that the test itself is never applied and thus does not matter, so NumericQ or OddQ for ...

- asked by gwr (11 votes), answered by Szabolcs (16 votes)

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[Matrix indexed by one number] http://mathematica.stackexchange.com/questions/111631/matrix-indexed-by-one-number

I’m trying to find a generic way (for arbitrary dimensions) to create a matrix like so

a[1] a[2]

a[3] a[4]

i.e where it is indexed by one number, instead of say Array[a, 2, 2] which gives

...

- asked by Henrik (10 votes), answered by Szabolcs (14 votes)

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[ErrorListPlot ignores some exact data points] http://mathematica.stackexchange.com/questions/111436/errorlistplot-ignores-some-exact-data-points

Possible bug? Or am I missing something / expecting too much?

Forgive the seemingly obscure data points but they’re where I’ve noticed a problem.

Needs["ErrorBarPlots`"] 
data = { 
   {{(10 Pi)/8, 1},  ...

- asked by Quantum_Oli (9 votes)

================================== Greatest hits from previous weeks: ==================================

[Generate two random numbers with constraints] http://mathematica.stackexchange.com/questions/97424/generate-two-random-numbers-with-constraints

I want to generate two random numbers, \(p\) and \(q\), between \(0.5\) and \(1\).

They are connected by the constraint \(1/(2q) > p\).

How do I generate \(p\) and \(q\)?

- asked by Chandan Datta (25 votes), answered by JasonB (11 votes)

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[Multivariable Taylor expansion does not work as expected] http://mathematica.stackexchange.com/questions/15023/multivariable-taylor-expansion-does-not-work-as-expected

The basic multivariable Taylor expansion formula around a point is as follows:

\[ f(\mathbf r + \mathbf a) = f(\mathbf r) + (\mathbf a \cdot \nabla )f(\mathbf r) + \frac {1}{2!}(\mathbf a \cdot \nabla )^2 f(\mathbf r) + \cdots \]

- asked by matheorem (24 votes), answered by Jens (29 votes)

================================== Can you answer these? ==================================

[Numerical Optimal Control] http://mathematica.stackexchange.com/questions/111375/numerical-optimal-control

It seems that most practical optimal control problems are only able to be solved numerically using a non-linear programming approach. As such, I was hoping to tackle the following optimal control ...

- asked by user7388 (3 votes)

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[How to define a custom 3D graphics primitive in Mathematica?] http://mathematica.stackexchange.com/questions/111403/how-to-define-a-custom-3d-graphics-primitive-in-mathematica

There are lots of basic graphics pimitive in Mathematica such as 2D- caseLine[], Circle[] and 3D case Cylinder[], BSplineSurface[],etc.

In general, they own the following usage if memory serves:

...

- asked by Shutao TANG (5 votes)

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[Can Mathematica reliably determine the equality of any two constructible numbers?] http://mathematica.stackexchange.com/questions/111615/can-mathematica-reliably-determine-the-equality-of-any-two-constructible-numbers

A constructible number is any number which can be expressed with only natural numbers and the operators \(+\), \(-\), \(\times \), \(/\), \(\sqrt {}\) (square root only). Is Mathematica’s Simplify or FullSimplify ...

- asked by Martin Buttner (3 votes)