4.12 Tuesday, October 3, 2017

================================== 
Top new questions this week: 
==================================

[Frown for a sex change, or, how do I unbork the "FacialGender" classifier in 11.2?] https://mathematica.stackexchange.com/questions/156847/frown-for-a-sex-change-or-how-do-i-unbork-the-facialgender-classifier-in-11

The limits of machine learning. I thought the new "FacialGender" option for Classifier would be an amusing thing to explore.

So far, so good. But that’s me with bed-head. So let’s try a picture ...

- asked by Verbeia (17 votes), answered by Searke (2 votes)

—————————-

[Improve the mesh smoothing procedure] https://mathematica.stackexchange.com/questions/156611/improve-the-mesh-smoothing-procedure

My question is inspired by this answer about meshing with quadrilateral elements.

The following functions are my (naive) try of implementing the Laplacian smoothing. I find interior nodes in the mesh ...

- asked by Pinti (11 votes), answered by user21 (10 votes)

—————————-

[Possible bug in RegionUnion or related functions?] https://mathematica.stackexchange.com/questions/157031/possible-bug-in-regionunion-or-related-functions

Functions for derived geometric regions (RegionUnion and related) have been significantly updated in MMA 11.2 and now this simple example doesn’t work any more as expected. Could this be a bug or I am ...

- asked by Pinti (8 votes), answered by Szabolcs (5 votes)

—————————-

[Dataset - append row with a value which depends on two other rows] https://mathematica.stackexchange.com/questions/156980/dataset-append-row-with-a-value-which-depends-on-two-other-rows

I have go through the forum but did not see this question. Hope I don’t miss it.

I want to add a new colum "C" to a dataset with existing columns named "A" and "B". The value of "C" shall be the ...

- asked by Porty (7 votes), answered by WReach (6 votes)

—————————-

[How to tell Mathematica to do this with decimal part of real number?] https://mathematica.stackexchange.com/questions/156823/how-to-tell-mathematica-to-do-this-with-decimal-part-of-real-number

My apologies if this was asked here before.

My friend and I want to do this:

Suppose that we have some real number \(a. a_1 a_2...a_n...\) where \(a_i\) are digits in the set \(\{1,2,3,4,5,6,7,8,9,0\}\) ...

- asked by Antoine de Paladin (7 votes), answered by Edmund (6 votes)

—————————-

[FullForm of b/c and c/b with different order] https://mathematica.stackexchange.com/questions/156757/fullform-of-b-c-and-c-b-with-different-order

I am studying Mathematica myself and doing some exercises for improvement.

  Question: Try to guess the internal forms of b/c and c/b. Verify your 
  answer using FullForm.

Here is what I got by ...

- asked by anhnha (7 votes), answered by Mr.Wizard (6 votes)

—————————-

[Generate random walk on a graph] https://mathematica.stackexchange.com/questions/156626/generate-random-walk-on-a-graph

I have a graph with 100 nodes and 200 edges. How can I generate a random walk in it and animate it?

- asked by nasha amalina (7 votes), answered by rhermans (13 votes)

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

[How to find the position of elements in a list satisfying criteria] https://mathematica.stackexchange.com/questions/180/how-to-find-the-position-of-elements-in-a-list-satisfying-criteria

Say I have a list x={2,4,6,8,10} and I want to find out the 
positions of the elements that are greater than 7. 
 
Select[x, #>7&] gives the elements themselves, and Position[x,8] gives the  ...

- asked by PeterR (47 votes), answered by J. M. (45 votes)

—————————-

[How to calculate contour integrals with Mathematica?] https://mathematica.stackexchange.com/questions/34073/how-to-calculate-contour-integrals-with-mathematica

How to calculate the integral of \(\frac {1}{\sqrt {4 z^2 + 4 z + 3}}\) over the unit circle counterclockwise for each branch of the integrand?

- asked by user64494 (30 votes), answered by Artes (53 votes)

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

[How to decode Ascii85 format (AKA base85)?] https://mathematica.stackexchange.com/questions/156667/how-to-decode-ascii85-format-aka-base85

The ASCII85 encoding is a binary string encoding where every four bytes are encoded with five ASCII letters, using 85 different types of characters.

Unfortunately, it’s not in $CharacterEncodings:

...

- asked by M.R. (2 votes)

—————————-

[FIR filter and the relation between Sample rate and cut-off frequency] https://mathematica.stackexchange.com/questions/156685/fir-filter-and-the-relation-between-sample-rate-and-cut-off-frequency

I have problem to unterstand the logic of the cut-off frequency of the FIR filter. Suppose my sample rate is 2MHz and I want to design a lowpass filter with a cut-off frequency 100Hz. What will be ...

- asked by shabir barzanjeh (2 votes)

—————————-

[FindCluster only finds cluster "with a little help"] https://mathematica.stackexchange.com/questions/156984/findcluster-only-finds-cluster-with-a-little-help

Currently I made some slides to illustrate clustering. As an example I made a point set of two clusters:

   {clusters, graph} = Block[{c1, c2, cluster1, cluster2}, 
   c1 = {1, 2}; 
   cluster1 = (# +  ...

- asked by mgamer (4 votes)