4.11 Tuesday, October 10, 2017

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Top new questions this week: 
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[How can I determine the type of a packed array?] https://mathematica.stackexchange.com/questions/157484/how-can-i-determine-the-type-of-a-packed-array

Packed arrays can be of type Integer, Real or Complex. Knowing that an array arr is packed, how can I efficiently determine its type?

- asked by Szabolcs (15 votes), answered by Szabolcs (17 votes)

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[Deleting sublists from lists] https://mathematica.stackexchange.com/questions/157267/deleting-sublists-from-lists

I have a list consisting of symbols and integers. I would like to delete the integers from the list only if a symbol precedes and follows each integer:

testList={a,b,3,c,4,5,d,e,f,1,g,4}

becomes:

...

- asked by Suite401 (12 votes), answered by jjc385 (13 votes)

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[Summation bug in 11.2] https://mathematica.stackexchange.com/questions/157290/summation-bug-in-11-2

If I sum all the positive-numbered Fourier coefficients of \(\cos (x)\), I get the correct answer. If I sum the negative-numbered ones, I get a wrong answer. Splitting the sum into two parts somehow ...

- asked by level1807 (10 votes), answered by Michael E2 (14 votes)

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[Calculating the size of objects in the picture] https://mathematica.stackexchange.com/questions/157374/calculating-the-size-of-objects-in-the-picture

I’m new to Wolfram Mathematica. I have an initial image:

My goal is to find a radius of the water drop, like so:

With that in mind, I’ve changed the initial photo:

resultImage = ...

- asked by Elias (9 votes), answered by b3m2a1 (7 votes)

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[Overlapping graphic primitives] https://mathematica.stackexchange.com/questions/157489/overlapping-graphic-primitives

I am trying to make a figure in Mathematica using some graphic primitives:

rod[l_, r_] :=   GraphicsGroup[{Opacity[.1], {Disk[{-l/2 + r, 0}, 
 r, {\[Pi]/2 , 3 \[Pi]/2}]}, {Disk[{l/2 - r, 0}, 
 r,  ...

- asked by Ruud3.1415 (7 votes), answered by kglr (3 votes)

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[How can I implement my own documentation search function?] https://mathematica.stackexchange.com/questions/157303/how-can-i-implement-my-own-documentation-search-function

The current documentation search doesn’t allow for very sophisticate searching, can I write my own function to search through the docs?

- asked by b3m2a1 (7 votes), answered by b3m2a1 (8 votes)

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[Can I implement something like the old documentation help browser?] https://mathematica.stackexchange.com/questions/157317/can-i-implement-something-like-the-old-documentation-help-browser

Old versions of Mathematica had a help browser that was more click through and structured. How can I reimplement something like that for the new (since v6) docs?

- asked by b3m2a1 (6 votes), answered by b3m2a1 (10 votes)

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

[What are the most common pitfalls awaiting new users?] https://mathematica.stackexchange.com/questions/18393/what-are-the-most-common-pitfalls-awaiting-new-users

As you may already know, Mathematica is a wonderful piece of software. However, it has a few characteristics that tend to confuse new (and sometimes not-so-new) users. That can be clearly seen from ...

- asked by Dr. belisarius (405 votes), answered by Michael E2 (235 votes)

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[How do I clear all user defined symbols?] https://mathematica.stackexchange.com/questions/850/how-do-i-clear-all-user-defined-symbols

Is there some way to do this other than going to Evaluation -> Quit kernel and firing a new one up?

- asked by niklasfi (58 votes), answered by Artes (56 votes)

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

[Memoization of built in function] https://mathematica.stackexchange.com/questions/157429/memoization-of-built-in-function

What is the best way to let mathematica memoize built-in function like e.g.

SphericalHarmonicY[l,m,th,ph] 
 
 
One possibility would be for sure: 
 
 sphericalHarmonicY[l_,m_,th_,ph_]:=  ...

- asked by Mr Puh (3 votes)

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[Can’t import Gluon into mma] https://mathematica.stackexchange.com/questions/157466/cant-import-gluon-into-mma

This is a simple DNN from Fast, portable neural networks with Gluon HybridBlocks:

This is json file and params file of Gluon(MXNet)

import mxnet as mx from mxnet.gluon import nn print("mxnet ...

- asked by partida (4 votes)

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[NIntegrate and definite Integrate give different results] https://mathematica.stackexchange.com/questions/157300/nintegrate-and-definite-integrate-give-different-results

Suppose the function

f[x_,q_]=(15876 Exp[-0.527076 q^2] (x^2-2 x+2) SphericalBesselJ[1,5 q]^2 (q^2-8100 x^2))/(3425*Pi*q^5*x);

I need to perform the integration over q in the domain ...

- asked by John Taylor (1 vote)