4.2 Tuesday, December 12, 2017

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Top new questions this week: 
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[Why does Mathematica results differ from C++ results within machine precision?] https://mathematica.stackexchange.com/questions/161716/why-does-mathematica-results-differ-from-c-results-within-machine-precision

I am trying to wrap my head around floating-point precision. Performing the following numeric operation:

275./6.*1.03692775514337

in Mathematica and C++ and taking the difference of the two results ...

- asked by Knowledge (22 votes), answered by ilian (44 votes)

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[Bug with Block & Lookup: Scope Variable Leak] https://mathematica.stackexchange.com/questions/161616/bug-with-block-lookup-scope-variable-leak

After debugging a large chunk of code, I could identify this MWE.

ClearAll@test 
test[var_String]:= Block[{association}, 
    association = <|"x"-> <|"key01"-> "ok"|>|>[var]; 
     ...

- asked by Murta (22 votes), answered by Albert Retey (15 votes)

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[Why is "k" in the output of Sum[Log[k]/k^k, {k,1,Infinity}]?] https://mathematica.stackexchange.com/questions/161704/why-is-k-in-the-output-of-sumlogk-kk-k-1-infinity

NSum[Log[k]/k^k, {k,1,Infinity}, WorkingPrecision->50] 
(* 0.219947267975228664843531307905860703797097130 *) 
 
 
But 
 
Sum[Log[k]/k^k, {k,1,Infinity}] 
(* -(PolyLog^(1,0))[0,1/k] *) 
 
 
What does "k" in  ...

- asked by Vaclav Kotesovec (13 votes)

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[Simulating molecular dynamics efficiently] https://mathematica.stackexchange.com/questions/161471/simulating-molecular-dynamics-efficiently

The following website offers a very nice molecular dynamics simulation: http://physics.weber.edu/schroeder/md/. It is pretty neat and quite a few physical phenomena can be described from that small ...

- asked by anderstood (13 votes), answered by Henrik Schumacher (16 votes)

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[Why is listable not an attribute of the Set function?] https://mathematica.stackexchange.com/questions/161428/why-is-listable-not-an-attribute-of-the-set-function

The following is a list of attributes for the Set function:

Attributes[Set]

HoldFirst, Protected, SequenceHold

Why is Listable not included?

- asked by S.V (13 votes), answered by Kuba (16 votes)

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[How to improve quality of this Plot3D] https://mathematica.stackexchange.com/questions/161771/how-to-improve-quality-of-this-plot3d

I tried driving up PlotPoints and MaxRecursion but the intersections look weird, is there some other trick I can do?

plot = Plot3D @@ {Abs[Sqrt[x] + Sqrt[y]] /. {x -> Sin[2 x], 
     y -> Cos[2  ... 

- asked by Yaroslav Bulatov (10 votes), answered by Nasser (11 votes)

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[How can I tell Mathematica to interpret 0xffff as a hexadecimal number?] https://mathematica.stackexchange.com/questions/161646/how-can-i-tell-mathematica-to-interpret-0xffff-as-a-hexadecimal-number

I am stuck. I would like Mathematica simply accept 0x as a prefix Operator for Hexadecimal Numbers. I know that 0x is interpreted as 0*x, so maybe this is just not possible. I am a programmer and am ...

- asked by Mark (9 votes), answered by Carl Woll (16 votes)

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

[Image processing: Floor plan - detecting rooms’ borders (area) and room names’ texts] https://mathematica.stackexchange.com/questions/19546/image-processing-floor-plan-detecting-rooms-borders-area-and-room-names-t

Here is a simple building floor plan. I would like to derive the rooms as (rectangular) components and the names of the rooms. This is very common representation of building floor plans.

The ...

- asked by s.s.o (52 votes), answered by nikie (52 votes)

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[How to create effect like Van Gogh’s stroke brush?] https://mathematica.stackexchange.com/questions/39003/how-to-create-effect-like-van-goghs-stroke-brush

I need to apply Van Gogh’s stroke brush effect to a random image

Take the following image as an example:

Thank you so much if you could help!

- asked by user10495 (30 votes), answered by Simon Woods (42 votes)

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

[How to export graphics to SVG in script executed through cron?] https://mathematica.stackexchange.com/questions/161756/how-to-export-graphics-to-svg-in-script-executed-through-cron

I have a Wolfram script that generates plots, and exports them by evaluating expressions of the form

Export["/path/to/some.svg", myPlot];

The script works as intended when I run it from the [Unix] ...

- asked by kjo (3 votes)

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[Is it possible to prevent LUDecompositon from pivoting?] https://mathematica.stackexchange.com/questions/161552/is-it-possible-to-prevent-ludecompositon-from-pivoting

By construction LUDecomposition performs LU-decomposition with pivoting, i.e. with row permutations (otherwise the decomposition may not exist). Is it possible to tell Mathematica not to use pivoting ...

- asked by faleichik (1 vote)

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[How Many of R’s Functionalities Are Available From Inside Mathematica?] https://mathematica.stackexchange.com/questions/161664/how-many-of-rs-functionalities-are-available-from-inside-mathematica

When R is linked to Mathematica, how many of its functionalities are available from inside of Mathematica?

- asked by Glenford Mc Ewen (2 votes)