3.13.1 Top new questions this week

3.13.1.1 Should I always be using Module in functions unless I explicitly want global variables?

http://mathematica.stackexchange.com/questions/126877/should-i-always-be-using-module-in-functions-unless-i-explicitly-want-global-var

 
I define functions a ton. In the past, I've mostly just defined my functions like: 
 
myFunc[var1_]:=( 
var2=var1^2; 
Return@var2; 
) 
 
 
And I haven't run into too much trouble. If I wanted to be really  ...
 

- asked by YungHummmma (15 votes), answered by WReach (18 votes)

3.13.1.2 Why this real integral yields imaginary results?

http://mathematica.stackexchange.com/questions/127301/why-this-real-integral-yields-imaginary-results

 
Integrate[(y - y^2 + x - x^2 + 2*x*y)/(1 - x - y),{x,0,1},{y, 0, 1}] 
 
 
The above integral yields -1-4I/3 in Mathematica. Since the integrand is real (although divergent at some points), how does  ...
 

- asked by Chong Wang (12 votes), answered by bbgodfrey (12 votes)

3.13.1.3 Would it be a good idea to use Failure and FailureQ in own code

http://mathematica.stackexchange.com/questions/126908/would-it-be-a-good-idea-to-use-failure-and-failureq-in-own-code

 
Since version 10 (at least 10.0.2 but I think 10.0.0) there is Failure and since version 10.2 there is also FailureQ. As often the documentation is somewhat vague and says "Failure is generated by  ...
 

- asked by Albert Retey (12 votes), answered by Leonid Shifrin (9 votes)

3.13.1.4 Display grayscale image as 3d plot

http://mathematica.stackexchange.com/questions/127210/display-grayscale-image-as-3d-plot

 
How to build 3d plot of grayscale image where x,y - pixel coordinates, z - pixel intensity? 
 
 
 
I tried ListPlot3D[ImageData[image]], but ImageData gives just intensities. I suppose a possible solution  ...
 

- asked by red1ynx (10 votes), answered by Kuba (11 votes)

3.13.1.5 Automatically draw ellipsoids around groups of select points

http://mathematica.stackexchange.com/questions/126899/automatically-draw-ellipsoids-around-groups-of-select-points

 
Suppose you have a ListPlot, and there are certain points you wish to emphasize belong to particular group. I would like to make a function that automatically draws an ellipsoid around a select group  ...
 

- asked by SumNeuron (10 votes), answered by Szabolcs (11 votes)

3.13.1.6 Enter colors directly into notebook?

http://mathematica.stackexchange.com/questions/127245/enter-colors-directly-into-notebook

 
In Mathematica notebook interface, you can evaluate: 
 
In[1]:= Black 
 
 
and you get a colored squared representing the color. Then I can copy and paste this color square and use it as input, like so: 
 
 
 
...
 

- asked by becko (9 votes), answered by WReach (10 votes)

3.13.1.7 Large Dataset query fails if column contains Missing

http://mathematica.stackexchange.com/questions/126851/large-dataset-query-fails-if-column-contains-missing

 
In version 11.0 (Win 8.1 Pro) a query on a large Dataset for a column that contains Missing fails most unceremoniously. 
 
With 
 
dsTest = AssociationThread[{"a", "b"}, 
If[Last@# == 10000,  ...
 

- asked by Edmund (9 votes), answered by JasonB (7 votes)