5.3 Tuesday, December 13, 2016

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Top new questions this week: 
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[Query: adding additional operator changes meaning of preceding operators] http://mathematica.stackexchange.com/questions/133124/query-adding-additional-operator-changes-meaning-of-preceding-operators

Consider the following query:

Range[5] // Query[Select[EvenQ] /* Append[1], f] 
 
(* {f[2], f[4], 1} *)

It selects the even numbers, applies f to them and finally appends 1 to the list. As expected, ...

- asked by WReach (15 votes), answered by WReach (15 votes)

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[Why does Mathematica think this series doesn’t converge?] http://mathematica.stackexchange.com/questions/132982/why-does-mathematica-think-this-series-doesnt-converge

Bug introduced in 10.0 and persisting through 11.0 (reported as CASE:3790525)

Here’s a simple series:

Sum[t^k DiscreteDelta[k]/k!,{k,0,Infinity}]

Mathematica says that it doesn’t converge. But ...

- asked by Ruslan (13 votes), answered by Jules Lamers (9 votes)

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[Joining two lists with relational operators] http://mathematica.stackexchange.com/questions/132928/joining-two-lists-with-relational-operators

I have two lists liste = {x, -y, y, -z} and 
listv = {1, -2, 3, -4}, which represent the inequities 
obtained evaluating liste - listv <= 0. How do I reassemble or 
join those two separate lists into  ...

- asked by nanjun (13 votes), answered by Kuba (15 votes)

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[What assumptions do I need to make Mathematica integrate a function?] http://mathematica.stackexchange.com/questions/133052/what-assumptions-do-i-need-to-make-mathematica-integrate-a-function

When I feed Mathematica the following integral:

Integrate[Sqrt[(A - x) (B - x)/x], {x, 0, B}]

it spits it back out without evaluating it. However, it can evaluate the integral

Integrate[Sqrt[(2 -  ...

- asked by user45146 (11 votes), answered by Artes (12 votes)

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[Do Apple Watch + Mathematica integrations still work?] http://mathematica.stackexchange.com/questions/133358/do-apple-watch-mathematica-integrations-still-work

I tried to follow this blog post: Instant Apps for Apple Watch, but none of the examples given worked, instead, they would simply hang on the "loading" screen.

Can anyone verify if this ...

- asked by M.R. (9 votes)

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[Locate Start and End Positions of Repeated Sequences in a list] http://mathematica.stackexchange.com/questions/133164/locate-start-and-end-positions-of-repeated-sequences-in-a-list

ListA = 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 12, 12, 12, 14, 14, 14, 12, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, 14, ...

- asked by SPIL (8 votes), answered by Suba Thomas (5 votes)

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[How can I add noise to a neural network input?] http://mathematica.stackexchange.com/questions/133090/how-can-i-add-noise-to-a-neural-network-input

A common "trick" in neural network training is to train an autoencoder using a "degraded" sample as input and the original sample as target output. The layer type DropoutLayer[] is made for this ...

- asked by nikie (8 votes), answered by nikie (5 votes)

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

[Can Mathematica do symbolic linear algebra?] http://mathematica.stackexchange.com/questions/3242/can-mathematica-do-symbolic-linear-algebra

For instance, is there some way I can say "let A and B be arbitrary real \(m\times n\) and \(k\times m\) matrices, Simplify[Transpose[Transpose[A].Transpose[B]]]" and Mathematica would simplify it to B.A? ...

- asked by nikie (38 votes), answered by helen (19 votes)

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[Calculate the 2D Fourier transform of an Image] http://mathematica.stackexchange.com/questions/29203/calculate-the-2d-fourier-transform-of-an-image

I am new to Mathematica, and using version 8.0.

I would like to calculate the 2D Fourier Transform of an Image with Mathematica and plot the magnitude and phase spectrum, as well as reconstruct the ...

- asked by user8727 (5 votes), answered by Nasser (27 votes)

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

[Mathematica script, called from Windows task scheduler, does not export graphics] http://mathematica.stackexchange.com/questions/133075/mathematica-script-called-from-windows-task-scheduler-does-not-export-graphics

When I run the following script from command line,

Needs["JLink`"]; 
ConnectToFrontEnd[]; 
resultChart = UseFrontEnd[JuliaSetPlot[0.365 - 0.37 I]]; 
UseFrontEnd[Export["test.png", resultChart]];

...

- asked by Karsten W. (2 votes)

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[Is it possible to do matrix algebra symbolically?] http://mathematica.stackexchange.com/questions/132955/is-it-possible-to-do-matrix-algebra-symbolically

I’m reading a book that has the following theorem:

I am trying to make Mathematica perform these calculations for me. Is it possible to do it without having to declare the matrices? For ...

- asked by Oppa Hilbert Style (2 votes)

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[Making graphic objects disappear interactively] http://mathematica.stackexchange.com/questions/133256/making-graphic-objects-disappear-interactively

I am trying to create a program where dots on a plane disappear when an object passes over them. I am using EventHandler to code the arrow keys for control of the object. I want each dot to ...

- asked by Savannah S (1 vote)