3.14.1 Top new questions this week

3.14.1.1 UI performance with large image data

http://mathematica.stackexchange.com/questions/127523/ui-performance-with-large-image-data

 
Some days ago, I built a small program for some of my colleagues to analyse cell images. One minor part of the user interface was the selection of the region of interest. The images are large and need  ...
 

- asked by halirutan (25 votes), answered by Kuba (21 votes)

3.14.1.2 Transform sphere to an ellipse in $R^2$

http://mathematica.stackexchange.com/questions/127645/transform-sphere-to-an-ellipse-in-r2

 
In Lay's Linear Algebra and Its Applications textbook, he defines the matrix 
$$A=\begin{bmatrix} 
4 & 11 & 14\\8 & 7 & -2 
\end{bmatrix}$$ 
and claims that the transformation $T(x)=A x$  ...
 

- asked by David (15 votes), answered by yarchik (17 votes)

3.14.1.3 Did Fibonacci slow down?

http://mathematica.stackexchange.com/questions/127876/did-fibonacci-slow-down

 
For Fibonacci numbers we have a nice formula: 
 
$$ 
\frac{\left(1+\sqrt{5}\right)^n-\left(1-\sqrt{5}\right)^n}{2^{n} \sqrt{5}} 
$$ 
 
We can implement that in Mathematica: 
 
a[n_]:=  ...
 

- asked by Fred Simons (13 votes), answered by Szabolcs (20 votes)

3.14.1.4 I would like to create a fractal by copying, scaling and rotating the initial element

http://mathematica.stackexchange.com/questions/127458/i-would-like-to-create-a-fractal-by-copying-scaling-and-rotating-the-initial-el

 
I want to create a fractal, which looks like this: 
 
 
 
This is rule 150R, which can be found in NKS, page 439. 
 
However, instead of using a cellular automaton, I want to create this fractal from a  ...
 

- asked by Yuriy S (13 votes), answered by wxffles (13 votes)

3.14.1.5 Mathematica + Pythonika on the Raspberry pi

http://mathematica.stackexchange.com/questions/127802/mathematica-pythonika-on-the-raspberry-pi

 
Due to the high availability of python code for the rpi, I'm trying to call python functions from Mathematica. I know that pythonika works well on OS X, but I can't compile it on the Raspberry pi. 
 
...
 

- asked by elbOlita (12 votes), answered by elbOlita (13 votes)

3.14.1.6 How to map and sum a list fast?

http://mathematica.stackexchange.com/questions/127658/how-to-map-and-sum-a-list-fast

 
The following takes a lot of memory and is slow: 
 
Timing[Total[Map[#^2 &, Range[1, 100000000]]]] 
 
 
I suspect this is because it first calculates and stores the whole list of squared numbers and  ...
 

- asked by Yrogirg (12 votes), answered by BlacKow (19 votes)

3.14.1.7 Implementing the BihamMiddletonLevine traffic model as CellularAutomaton

http://mathematica.stackexchange.com/questions/127821/implementing-the-biham-middleton-levine-traffic-model-as-cellularautomaton

 
In an attempt to understand how to make rules for CellularAutomaton[], I set out to try to implement the BihamMiddletonLevine traffic model. 
 
It is a 2D, k=3 model with a 3x3 neighborhood, so the  ...
 

- asked by HJensen (10 votes), answered by C. E. (5 votes)