Linked Questions

523
votes
19answers
130k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
69
votes
7answers
5k views

Partitioning with varying partition size

How can I partition a list into partitions whose sizes vary? The length of the $k$'th partition is a function $f(k)$. For example: if $l = \{1, 2, 3, 4, 5, 6\}$ and $f(k) = k$. Then the partitioning ...
19
votes
17answers
6k views

Generating a list of numbers that are not multiples of 4

I want to write simple code that will list all numbers from $1$ to $n$ that are not multiples of $4$. And in this case I consider that ...
39
votes
5answers
5k views

How to implement the general array broadcasting method from NumPy?

A friend of mine introduced array broadcasting in the Python NumPy package which is very convenient (and also highly efficient). The idea is perfectly shown in ...
30
votes
6answers
5k views

Finding all elements within a certain range in a sorted list

Suppose we have a sorted list of values. Let's use list = Sort@RandomReal[1, 1000000]; for this example. I need a fast function ...
49
votes
3answers
2k views

Are there guidelines for avoiding the unpacking of a packed array?

Packed arrays are very useful because they save memory and generally allow speedier and more efficient calculation times. If a list of data currently stored as a packed array is unpacked, it can slow ...
13
votes
6answers
1k views

Efficient conditional Mean[] on a large data set

Consider a list, AK6, that has 382 sublists of length varying from 2500 to 3000. Each "subsublist" is as such : ...
31
votes
3answers
2k views

Why is Plus so much slower than Total?

Why is Plus so much slower than Total for summing lists? ...
41
votes
1answer
3k views

Why won't Parallelize speed up my code?

What reasons are there that can cause parallelized Mathematica code not to run with full performance?
21
votes
5answers
4k views

How to zero (or replace) the diagonal of a square matrix?

Zeroing the diagonal of a square matrix is an operation I need frequently, but somehow I still haven't managed to find an elegant solution that satisfies all these requirements: works with both ...
9
votes
5answers
1k views

How can I define a very large matrix efficiently?

Here's a 7x7 matrix: ...
11
votes
3answers
3k views

Dramatic speed difference of code on Matlab and Mathematica

Background: I was trying to convert a Matlab code (fluid simulation, SPH method) into a Mathematica one, but the speed difference is huge. Matlab code: ...
10
votes
5answers
884 views

Substitute some 1s with 0s in random list

How is it better to substitute list of random combination of 1 and 0 (binary image) so that only first (or central) instance of 1 left in each group. ...
38
votes
1answer
1k views

Numerics with Mathematica

From time to time, I would like to use Mathematica purely numerically, e.g., plotting a function which is defined as an integral which cannot be solve analytically or a solution of a differential ...
3
votes
5answers
2k views

Find the slope between adjacent points in a list

I have a list of two dimensional points that are ordered by their x-coordinate. I would like to calculate the slope between all adjacent points. I'm familiar with the use of pure functions in Sort ...

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