Questions tagged [language-design]
for questions about the design of the Mathematica language itself
64
questions
118
votes
1
answer
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views
Why are numeric division and subtraction not handled better in Mathematica?
There is something that has been troubling me for a while. At least through version 10.0 the performance of a / b and a - b is ...
- 269k
44
votes
5
answers
2k
views
Why is there no PositionFunction in Mathematica?
Too often I have seen the programs of inexperienced users greatly slowed by using Position in an iterative fashion, when far faster would have been to compute a ...
- 269k
16
votes
3
answers
2k
views
Specifying string patterns in DeleteCases
It seems that DeleteCases is not compatible with string patterns, at least directly (see, for example, this question). Is this true? If so, why is this the case? ...
- 10.2k
48
votes
3
answers
1k
views
Is FullGraphics an abandoned function? Is there an alternative?
FullGraphics hasn't worked entirely for a long time and the situation appears to be getting worse instead of better. In Mathematica 10.0, 10.1, 11.3, 12.3 up to 13....
- 269k
43
votes
0
answers
1k
views
Performance problems in new Sequence functions
The new-in-10.1 Sequence* family of functions should provide newly optimized methods for handling sequence problems. Happily in some cases they do! For example ...
- 269k
27
votes
2
answers
603
views
Version inconsistency with optional arguments: what if the default value doesn't match the pattern?
I just came across some weird behaviour. Take this function definition:
ClearAll[f]
f[vs_List : All] := "match"
The default value of ...
- 232k
13
votes
1
answer
393
views
Is there a good reason for the removal of this FrameTicks syntax?
In past versions of Mathematica one could use a terse syntax for FrameTicks:
{bottom, left, top, right}
In 10.1 this syntax is no longer recognized requiring the ...
- 269k
24
votes
2
answers
666
views
Why doesn't a Composition[] hold its arguments and what can be done about it?
Now that Composition (also RightComposition) has shorthand syntax I am more inclined to use it, however what I feel should be ...
- 269k
19
votes
2
answers
334
views
Association's Attributes change between 10.3.1 & 10.4?
In Mathematica 10.3.1
In[1]:= Attributes[Association]
Out[1]= {Protected}
In Mathematica 10.4:
...
- 7,928
42
votes
1
answer
2k
views
How can I define a new symbolic constant like Pi?
There are a few builtin symbolic constants which behave like numbers, e.g. E, Pi, EulerGamma,...
- 232k
12
votes
2
answers
318
views
ToExpression and ToBoxes aren't inverses of each other?
Applying ToExpression and ToBoxes repeatedly to Hold[1/1] gives many ...
- 1,939
47
votes
1
answer
5k
views
++ is dangerous for C programmers
I noticed this fact, that may be misleading for programmers used to C language.
In Mathematica, if you have a function f[] and an array ...
- 733
38
votes
2
answers
9k
views
Why do Mathematica list indices start at 1? [closed]
In most programming languages, container indices start at 0. This is not random or hardware-related; for example Dijkstra's article explains why zero-based indices make sense.
What are the reasons ...
- 757
20
votes
2
answers
467
views
Unexpected behaviour when pattern matching with Longest
I came across some unexpected behaviour today when using the Longest function when trying to do some pattern matching.
...
- 412
16
votes
3
answers
408
views
Why is the first argument of the SetDelayed evaluated?
In[1]: f=g;
In[2]: SetDelayed[f[x_],x^2];
In[3]: ?f
Global`f
f=g
In[4]: ?g
Global`g
g[x_]:=x^2
However, SetDelayed has the ...
- 397
88
votes
4
answers
47k
views
Why round to even integers?
According to the Mathematica help:
Round rounds numbers of the form x.5 toward the nearest even integer.
For example:
Round[{0.5, 1.5, 2.5, 3.5, 4.5}]
gives
...
- 14.2k
20
votes
1
answer
740
views
Why won't SparseArray let me store values with the head List?
When you attempt to define a SparseArray with elements that have the head List it complains:
...
- 269k
18
votes
2
answers
5k
views
Why does Mathematica order polynomial forms in reverse from traditional order?
I could very well be missing something obvious, but this has always bugged me with Mathematica and I don't know why it does it or how to fix it.
If I enter any polynomial, say, x^2 + x - 1 for ...
- 525
18
votes
2
answers
1k
views
Why it seems that there is no counterpart function as to multiplication, to `Total` as to addition?
Times and Plus have the same grammar, and so do Product and ...
- 9,523
15
votes
3
answers
5k
views
Why don't * and ^ work as I expected on matrices? [closed]
For example, this input...
{{1, 2}, {3, 4}}*{{1, 2}, {3, 4}}
produces this output...
{{1, 4}, {9, 16}}
and this input...
<...
- 1,007
13
votes
2
answers
3k
views
Why did Mathematica choose brackets for function arguments over parentheses?
This is a non-technical question. I'm just curious why Mathematica breaks the convention that parentheses are widely used for function arguments. What's the advantage of ...
- 459
4
votes
1
answer
327
views
Why is there a difference when formulating patterns for Select and FirstPosition?
Select[{1, 2, 4, 7, 6, 2}, # > 2 &]
Gives {4, 7, 6}. OK!
So one should think that the following would work:
...
- 239
47
votes
3
answers
3k
views
What are all the "magic" symbols in the Mathematica language?
Leonid Shifrin once wrote (excerpted):
(Unevaluated) is one of a very few "magic symbols", along with Sequence and <...
- 269k
22
votes
2
answers
574
views
Second argument of BeginPackage with nested package loading
I naively thought that the second argument of BeginPackage can simply be used to ensure the loading and availability in the ...
- 232k
15
votes
2
answers
325
views
Is anonymous pure function a scoping construct?
In recent thread was raised the question: why anonymous pure functions Function[body] (or body &) do not rename symbols in ...
- 61.3k
12
votes
2
answers
278
views
Why is Graph an atomic expression in Mathematica?
Actually, the title says it all. I am a little confused why such a complicated object as Graph, with many different parts, was designed to be atomic in Mathematica ...
- 1,027
11
votes
2
answers
461
views
Unexpected variable renaming depending on form of a pure function
I encountered unexpected difference in variable renaming behavior depending on whether a pure function with a named parameter, or a pure function with a slot is used:
...
- 7,163
9
votes
1
answer
258
views
Different Set Semantics - Why is assoc["a"] =. different from assoc[["a"]] =.?
Accessing parts of an Association can be done either using Part or the [] extraction ...
- 6,046
21
votes
1
answer
434
views
Why are some option values symbols, other strings?
Is there a rationale, beyond historical accident, why some Mathematica option values are strings, while others are symbols?
It seems natural that some value spaces, e.g. named color schemes, are so ...
- 15k
13
votes
1
answer
333
views
Why can AppendTo modify a referenced list in-place but Part cannot?
Part, AppendTo, PrependTo, AddTo, etc. allow in-place modification of a list, but only Part requires that the list be referenced through a simple symbol, e.g. the following all does what you'ld expect:...
- 175
2
votes
1
answer
176
views
Why does `Position` by default return a list of lists of positions instead of a simple list of positions?
Position[{1,2,3,4,2,3,4,5},2]
(* Output: {{2},{5}} *)
Why does Position work this way? I understand this form might be ...
- 3,256
31
votes
2
answers
2k
views
Why did the Mathematica Language choose term rewriting instead of the Lambda Calculus as its basis?
Now we can see that Church was associated with the Simply Typed Lambda Calculus. Indeed, it seems he explained the Simply Typed Lambda Calculus in order to reduce misunderstanding about the Lambda ...
- 429
29
votes
1
answer
1k
views
Why some built-in functions are slow
I just wonder why some built-in functions are slower compared to some other ways using more than one built-in functions for doing same job.
consider this example:
...
- 19.7k
26
votes
6
answers
791
views
Is mathematica adequately improving?
A bit of a loaded question, but in your opinion is Wolfram's team making good progress on improving their software?
I've used Mathematica for almost 10 years now, and honestly I'm personally ...
- 860
22
votes
1
answer
494
views
What's the difference between these 2 associations?
I have 2 associations similar to these simplified ones:
...
- 19.8k
17
votes
0
answers
209
views
Why are delayed definitions in scoping functions NOT documented?
As outlined here, := may be used in scoping constructs like With to give delayed definitions, but this is undocumented.
This ...
- 269k
16
votes
8
answers
3k
views
Product of elements of a list
Sum is for functions; Total is for a list. Product is for a function; what is the command ...
user21376
16
votes
1
answer
591
views
Why doesn't Mathematica pack Boolean arrays?
I've been wondering about this for a while now, so I'm going to ask. This is a question about the design of Mathematica, which perhaps cannot be directly answered by anyone but the designers, however ...
- 269k
13
votes
1
answer
555
views
What naming conventions are used for functions? [closed]
I thought there were patterns to how functions were named, but after looking carefully it seems I can always find exceptions. For instance
FindThreshold = Action + Object
SetAlphaChannel = Action + ...
- 31k
12
votes
2
answers
877
views
Why aren't parentheses ( ) an expression in Mathematica?
Why aren't parentheses ( ) an expression in Mathematica?
Can I get an expression in a form where parentheses are represented by an expression?
- 1,857
8
votes
0
answers
145
views
Relation between the syntactic and evaluated Association
This question is inspired by this answer and related to unsolved post "Association's Attributes change between 10.3.1 & 10.4"...
- 2,764
7
votes
0
answers
194
views
Why patterns names aren't scoped by default?
In a recent question [1] OP asked how to make Module scope working inside Set, so how to get:
...
Kuba♦
- 136k
7
votes
1
answer
175
views
What is the logiс behind handling alpha-channel by various image-processing functions?
(Cross-posted on Wolfram Community.)
When working on the answer to this question I discovered that starting from Mathematica 10.0 the behavior of such functions as ...
- 61.3k
6
votes
2
answers
532
views
PlotLegends "Expressions" default for ListPlot?
gwr pointed out an apparent problem with setting a default Option value of PlotLegends for DateListPlot. I traced the problem ...
- 269k
6
votes
2
answers
285
views
WL terminology: evaluate, call, invoke, use, etc
A WL (Mma) program is a sequence of expressions to be evaluated, which generally involves applying commands and functions to actual arguments. What is the accepted terminology for what I think of as ...
- 13.5k
3
votes
1
answer
1k
views
Why is Euler's number an uppercase "E" and not a lowercase "e"?
Why is Euler's number an uppercase "E" and not a lowercase "e"?
Isn't Euler's Number normally expressed with a lowercase "e"?
- 1,545
44
votes
1
answer
2k
views
What's the deal with next generation Wolfram compiler?
Sources:
Old Compiler (Rob Knapp Nov2011)
Computer Science in Mathematica (Abdul Dakkak Dec2014)
Compilation Technology (Tom Wickham-Jones, Abdul Dakkak & Steve Wilson Dec2015)
The Wolfram ...
- 8,973
25
votes
1
answer
780
views
What's the point of ContainsAll, ContainsAny and friends?
Mathematica 10.2 contains a few new functions that test set containment: ContainsAll, ContainsAny and a few others. The ...
- 35.9k
22
votes
3
answers
4k
views
Why does Mathematica use [[ ]] notation for array indexing?
I am confused by why Mathematica uses [[3]] to get the 3rd element, or [[i,j] to get the i,j-th element of a 2D array.
This ...
user1602
22
votes
1
answer
796
views
What are the benefits of Entity Classes for Databases?
To me, using the older database functionality is much simpler:
...
- 31k