31
votes
Why is Plus so much slower than Total?
Performance issues with large numeric arrays very often happen because of unpacking of PackedArrays. Numeric operations on Packed arrays are very well optimized, while unpacking and operations on huge ...
- 7,886
27
votes
List of symbols without built-in meaning
Updated to include both unary and binary operators
One idea is to use the usage message of a symbol as a clue that it has a special display form, probably with no built-in meaning. For example:
<...
- 132k
24
votes
Accepted
What's purpose of the new function BinarySerialize?
Disclaimer:
This answer is written from a user's point of view. For useful insider information on this topic see this discussion with Mathematica developers on Community Forums.
Introduction
Binary ...
- 7,886
22
votes
Why is Plus so much slower than Total?
In Mathematica, "everything is an expression". All data and code is represented in the same manner, as Mathematica expressions. Thus expressions must be very general. They need to be able to ...
- 236k
17
votes
Accepted
Who or what is named character Andy?
The original MMa fonts were designed by Andre Kuzniarek and Andrew Hunt.
From Andre:
Indeed, those are old easter eggs, and there used to be glyphs for each of us. They were "abandonded" in later ...
- 1,800
17
votes
Accepted
Head[x] vs x[[0]]
Preamble
The biggest problem with Head seems to be that it plays two distinct, although related, roles in the language:
The 0 - th element of an expression
The ...
- 115k
16
votes
Why is Plus so much slower than Total?
Introduction
@Shadowray has already put a finger on the source of the time difference in the OP's example: unpacking. But it seems to me that the question points out just a symptom of a broader ...
- 245k
16
votes
Accepted
Is it safe to Unprotect everything? What are the implications?
The reason is to prevent users to mess with it. Unprotecting something is not necessarily dangerous, but unprotecting everything definitely is. Performance is probably not the issue. The real danger ...
- 110k
15
votes
Is it safe to Unprotect everything? What are the implications?
There is a typesetting step after formatting, and MakeBoxes definitions do not require unprotecting Hold, you will just add more ...
- 138k
15
votes
Accepted
Finding year that MMA functions were introduced via programmatic calls in the Wolfram Language
find the year that MMA functions were introduced via programmatic
calls
You can use, as an example
...
- 150k
15
votes
Accepted
very simple but unexpected aspect of Function[ ]
The issue is that to SetDelayed1 (:=), Function is just a normal head. For your third ...
- 34.4k
15
votes
How can I create a shortcut to convert "normal Symbol" to Formal Symbol?
Here's an attempt:
...
- 34.4k
13
votes
List of symbols marked [[EXPERIMENTAL]] in the documentation
List available as EntityList[EntityClass["WolframLanguageSymbol", "Experimental"]]
- 131
12
votes
Accepted
Is there a built-in function to get the centroid of a table?
wd = WeightedData[Tuples @ Range @ Dimensions @ table, Join @@ table]
Mean @ wd
{22.3232, 33.9072}
Also
...
- 401k
12
votes
Accepted
12
votes
Which function names have been re-purposed in Mathematica after being deprecated?
The oldest example I can think of is Medium.
Version 1.x:
It got deprecated after version 2, and was then re-introduced in version 6; that usage persists to this ...
12
votes
Accepted
Using < or <= make different results when sort
The pair {{d, 4}, {c, 4}} does violate the order #1[[2]] < #2[[2]]:
4 < 4
(* False *)
...
- 1,291
11
votes
Accepted
Why isn't Orderless an Attribute of And?
As you mentioned, And is not Orderless just for efficiency; its arguments are evaluated one by one to prevent unnecessary ...
- 4,694
11
votes
Accepted
What's the purpose of the GeneralUtilities`UnpackOptions?
(analysis current as of Mathematica V11.0.1)
UnpackOptions is a macro that provides a convenient notation for accessing option values within a function definition.
...
- 69.3k
11
votes
List of symbols without built-in meaning
Here is an approach based on reading the Front End resource UnicodeCharacters.tr.
This method finds some operators that do not presently appear in Carl Woll's list ...
- 273k
11
votes
Accepted
1 is not the SameQ as Null, but why might 1 be Equal to Null?
=== (SameQ) tests structural equality and is meant mainly for programming uses. Like nearly all functions named as ...
- 236k
11
votes
Table of precedence values for all System` symbols
You can use Precedence to get the precedence for a symbol. The following code produces an association with precedences as keys, and symbol names corresponding to ...
- 132k
11
votes
Construct a pure function containing built-in 'Sequence'
##& is functionally equivalent to Sequence in most cases, and does the job here.
...
- 441
11
votes
Accepted
What is MergeDifferences?
MergeDifferences is an option to SequenceAlignment. Autocompletion is not context-sensitive in this sense (although syntax ...
- 19.1k
10
votes
Accepted
How to find all function which cannot be ToExpression?
Reflection in Mathematica is a tricky business. This makes the definition of a "normal result" tricky as well. This response will point out some of those difficulties and provide some tools to deal ...
- 69.3k
10
votes
Geometry computations add-on for Mathematica?
The following is a built-in way of finding circumcenters:
gr = Graphics[{
Circumsphere[{{0, 0}, {1, 0}, {0, 1}}],
Triangle[{{0, 0}, {1, 0}, {0, 1}}]
}];
...
- 71.2k
10
votes
Accepted
What is the inverse of the Position function?
I don't know that you can do it in a single command. But it's easy enough to do in two. Say your list is list={2,1,4};
...
- 69.7k
10
votes
Accepted
How to obtain list of Installed Packages loadable by Get (<<)
There's nothing truly built in, but this is easy to roll if you know how to work with paclets. PacletInformation will return a ...
- 47.1k
10
votes
Accepted
Largest k such that p^k divides n
IntegerExponent
IntegerExponent[120, #] & /@ {2, 3, 5, 7}
(* {3, 1, 1, 0} *)
- 36.8k
9
votes
Only top scored, non community-wiki answers of a minimum length are eligible