3.2.1 Top new questions this week

3.2.1.1 Why is SatisfiabilityCount faster than SatisfiableQ?

http://mathematica.stackexchange.com/questions/103726/why-is-satisfiabilitycount-faster-than-satisfiableq

 
Consider the following (large) Boolean expression, which arose in a SAT problem. (The expression is not satisfiable.) 
 
bigExpr = Import["http://pastebin.com/raw/gEgGQ26S"]; 
 
 
On my system (Mathematica  ...
 

- asked by David Zhang (13 votes), answered by Adam Strzebonski (16 votes)

3.2.1.2 ReplaceAll with Associations instead of Rules

http://mathematica.stackexchange.com/questions/103497/replaceall-with-associations-instead-of-rules

 
I have just noticed that 
 
x /. <|x -> 123|> 
 
 
evaluates to 
 
123 
 
 
In other words, the association seems to behave as a rule. I didn't see any example or reference to this behavior in the  ...
 

- asked by Gustavo Delfino (13 votes), answered by Edmund (4 votes)

3.2.1.3 Is it possible to Parallelize Select?

http://mathematica.stackexchange.com/questions/103548/is-it-possible-to-parallelize-select

 
Given a large list of elements, is it possible to improve Select by parallelizing? 
 
An example: from a 10,000,000-element list of integers between 1 and 10, select all primes 
 
rl = RandomInteger[10,  ...
 

- asked by jjstankowicz (11 votes), answered by bbgodfrey (15 votes)

3.2.1.4 how to enforce a symmetric solution with fem?

http://mathematica.stackexchange.com/questions/103606/how-to-enforce-a-symmetric-solution-with-fem

 
I'm solving the laplace equation in a domain with holes, and I need to compute the integral of the gradient on the boundary of these holes. 
 
For that I define a mesh and solve the laplace equation  ...
 

- asked by tsuresuregusa (10 votes), answered by user21 (5 votes)

3.2.1.5 Best way to emulate MATLAB's bsxfun using Map and similar functions

http://mathematica.stackexchange.com/questions/103527/best-way-to-emulate-matlabs-bsxfun-using-map-and-similar-functions

 
Given a matrix, we want to subtract the mean of each column, from all entries in that column. So given this matrix: 
 
(mat = {{1, 2, 3, 4}, {5, 6, 7, 8}, {9, 10, 11, 12}}) // MatrixForm 
 
 
 
 
the mean  ...
 

- asked by Nasser (10 votes), answered by Mike Honeychurch (11 votes)

3.2.1.6 Order of evaluation - does Mathematica evaluate variables before or after substitution?

http://mathematica.stackexchange.com/questions/103800/order-of-evaluation-does-mathematica-evaluate-variables-before-or-after-substi

 
Let's say I write 
 
y = x^2; 
x = 10; 
z = y + y^2 + y^3 
 
 
Does Mathematica internally evaluate y before or after substituting it into z?  I.e., does Mathematica internally evaluate this as 
 
y = x^2 =  ...
 

- asked by tparker (9 votes), answered by Alexei Boulbitch (12 votes)

3.2.1.7 How to "inform" successive ContourPlot calculations?

http://mathematica.stackexchange.com/questions/103673/how-to-inform-successive-contourplot-calculations

 
I need to draw some contour plots of very non-linear functions.  As a simple example, take a Mandelbrot Set divergence contour near $z\approx i$.  (Just to be clear, I'm not trying to write a  ...
 

- asked by Jerry Guern (9 votes), answered by bbgodfrey (10 votes)