Questions tagged [language-design]
for questions about the design of the Mathematica language itself
148
questions
4
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2
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Module inside Module. Conflict of names in arguments
I have a module which calls number of other smaller helper modules. But those other helper modules are not used by another module, so there is no needed to have them in global context. So I wanted to ...
- 143k
4
votes
1
answer
340
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
4
votes
1
answer
257
views
Differences between minimization functions?
There's more than 20 functions having to do with minimization
...
- 3,947
4
votes
1
answer
61
views
A natural syntax for a Query that holds
Often I have an unevaluated expression in a RuleDelayed Key-Value pair and subsequently want ...
- 6,076
4
votes
1
answer
89
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Why was StringRepeat designed so that StringRepeat[s, 0] throws an error?
Update
In version 13.2 StringRepeat[" ", 0] produces an empty string.
I'm wondering about the rationale behind the design decision that leads to the ...
- 968
4
votes
1
answer
204
views
Why even try the semantic constraints, if expression can't match the pattern structure?
This result is unexpected:
Trace[MatchQ[{7}, {_?NumberQ, __}], NumberQ] (* -> {{NumberQ[7], True}} *)
Why evaluate NumberQ...
- 783
4
votes
0
answers
74
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Why does `MakeBoxes` have the HoldAllComplete attribute and ignore it rather than HoldAll?
MakeBoxes has the attribute HoldAllComplete. For a normal function, it would imply that Upvalues should not be taken into account when the expression is evaluated:
<...
4
votes
0
answers
102
views
Obtain complete list of built-in graphical objects, and split them into groups?
I would like to obtain the complete listing of built-in graphical objects (which can be used in Graphics or Graphics3D) ...
- 61.9k
4
votes
0
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97
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Why is SparseArray atomic?
This answer tells us that functions like ReplaceAll do not straightforwardly work for the entries of sparse arrays because a ...
- 1,074
4
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0
answers
254
views
Specifying a region of the complex plane [closed]
I can use the following to specify a region of the complex plane.
R1=ImplicitRegion[1.0<=Norm[{a+1,b-1}]<=2.0,{a,b}];
RegionMember[R1,{0.5,1}]
It would be ...
- 7,124
4
votes
0
answers
1k
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DSolve versus DSolveValue [closed]
I've just discovered the new command DSolveValue in Mathematica 10. Is this new command now the preferred instead of DSolve? Is ...
- 14.9k
3
votes
2
answers
452
views
Why are Quantity and Units inconsistent with regular Mathematica behavior?
When I enter this in Wolfram Mathematica V12:
0 Dogs + 5 Cats
Mathematica sensibly returns this:
5 Cats
BUT, if I using the ...
- 65
3
votes
1
answer
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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
3
votes
3
answers
157
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Why Graph does not recognize chains of vertexes like NetGraph
Cross posted on Wolfram Community.
Perfect logic:
NetGraph[{1, 1, 1}, {1 -> 2 -> 3}]
But this does not make sense:
...
- 2,060
3
votes
1
answer
83
views
Understanding how List head works
I am trying to understand how Wolfram Language is actually meant to work and here is something that I fail to understand.
Apply[f, expr] replaces the head of expr by f.
So how come I get different ...
- 1,419
3
votes
3
answers
123
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Orderless storage of tabulated function values
I would like to elaborate on my previous question Function of arguments given in non-fixed order and a relevant related one Best practice of passing a large number of parameters to functions
I find ...
- 1,420
3
votes
1
answer
166
views
Span starting from the end
I could not find something similar.
Given, e.g.
lst = Range[10]
(* {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} *)
the following gives the reverse of ...
- 4,794
3
votes
1
answer
282
views
Refactoring: Why? When? How?
A good Refactoring can transform a kludgy WL code-base into a thing of pristine coherency but how to do so consistently?
- 6,076
3
votes
1
answer
187
views
Single argument operator form?
I've heard the explanation that functions like StringDrop[] are varargs and so that is why they do not have an operator form.
But when you are only using the ...
- 3,583
3
votes
1
answer
159
views
Why is left NumberPadding always applied in NumberForm?
I would like to display numbers like 9.0001 and 10.0001 in the fixed-width form of xx.xxxx. ...
- 7,780
3
votes
0
answers
67
views
what are the principles of good design with Wolfram Language a la Zen of Python? [closed]
The Zen of Python — is a list of 19 general truths for Python design principles.
( https://medium.com/@Pythonidaer/a-brief-analysis-of-the-zen-of-python-2bfd3b76edbf )
3
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0
answers
146
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Why is MeshRegion atomic?
I wanted to make some changes inside a MeshRegion today and found that unlike Graphics objects, it can't be done directly ...
- 7,911
3
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0
answers
435
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Mixing Wolfram Language & WolframAlpha Queries - How robust is it?
The advent of Mathematica in the cloud and linguistic input potentially transforms expectations of the Wolfram Language's programming model and its inherent robustness. An example of this comes form ...
- 6,076
2
votes
1
answer
199
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 ...
- 3,596
2
votes
2
answers
197
views
Sets of identical equality/inequalities
So I've used Mathematica for some months, but I never noticed this sort of thing about it, namely:
(a > b) == (b < a)
which are supposed to be identical ...
- 283
2
votes
1
answer
252
views
Separating the Numerator & Denominator
It's been years since I last programmed in Wolfram & for the first few days, I felt like I've been feeling around the dark; now that I've mostly forgotten how to code it.
Again, I could be ...
- 181
2
votes
1
answer
164
views
How to think about the answer to Rationalize[-11.5, 1]
In the open source Mathematica implementation called Mathics, an issue was raised where Mathics computes Rationalize[-11.5, 1] as -12 rather than Mathematica which ...
- 245
2
votes
1
answer
259
views
DeleteCases not working as expected
I am trying to reproduce the example of Data Cleaning from here.
I had to make a slight change in input 13 to
...
2
votes
0
answers
99
views
Why does Plot function have HoldAll attribute?
I had an odd issue where my plot wasn't drawn correctly when I called it via Plot[Join[fs,gs], (*..*)]. However, these two versions worked:
...
- 121
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votes
0
answers
119
views
Why is ComplexQ not available? [closed]
For names = Names["System`*"]; executing the following returns 200 hits.
...
- 53.7k
2
votes
0
answers
66
views
Should SubsetMap be called CombineAt?
I'm a big fan of the functionality introduced by SubsetMap but am puzzled as to why it was not called "CombineAt". There are ...
- 6,076
2
votes
0
answers
125
views
Areasinus hyperbolicus [closed]
Why is there a function ArcSinh[]?
Shouldn't this be called ArSinh, since it is connected with an area and not with the length (...
- 1,577
2
votes
0
answers
94
views
Why does Mathematica round numbers in this way where the fractional part is 0.5? [duplicate]
I was trying to comment on sequence https://oeis.org/A047229 in the OEIS, when one of the editors pointed out that the rounding is done wrong in this Mathematica one-liner:
...
- 1,159
1
vote
2
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155
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Why can we assign a value to a function that has not been defined yet?
Consider the following snippet,
fib[1] = fib[2] = 1;
fib[n_Integer] := fib[n - 1] + fib[n - 2]
As a newbie, it seems for me, the first line assigns 1 to ...
- 2,029
1
vote
2
answers
337
views
inappropriate domain restriction on FromPolarCoordinates?
The only way I can understand the domain restriction on FromPolarCoordinates is as ensuring a round-trip is possible: ...
- 13.7k
1
vote
1
answer
95
views
Variable substitution like usual maths
So... I'm trying to get some simplifications on equations using own defined variables, but the tries I gave didn't result on what I wanted.
The problem: I have 2 variables defined as:
...
1
vote
0
answers
49
views
Why do rules not default to local scope? [closed]
Consider the following:
80 //. a_?EvenQ -> a/2
a = 3
80 //. a_?EvenQ -> a/2
which outputs:
5
3
3/2
I think I understand ...
- 121
1
vote
0
answers
118
views
Why is the dot operator not just matrix multiplication?
It seems to me Mathematica does not have an inbuilt matrix multiplication operator. The dot operator fails as such, as is even noted under "Possible Issues" in its documentation it ...
- 111
1
vote
2
answers
101
views
Please I need help to define a function of two variables (t,x)!
Let's define the following function:
f[t_, x_] = t^2 + t*x*(1 - x)
such that $x \in (0,1)$ and `$t \in (0,0.02)$
The problem is when I want to define the following ...
- 151
1
vote
0
answers
57
views
"Compile-time" patterns
If I define a function like
f[x : {_, _Integer}] := (* function body *)
then, as I understand it, every time f[expr] is ...
- 9,010
1
vote
0
answers
141
views
Intervals v.s. Domains: when to use which and why?
or: How to use Interval correctly?
Mathematica provides these constructs for various symbolic deductions tasks. Among those constructs are symbolic number sets ...
- 862
1
vote
0
answers
88
views
Is there packages can help read, analyze or understand MMA codes? [closed]
Sometimes, I think that it's difficult to learn high level codes, or even when looking back on some long lines of codes I myself had written, espectially when lots of pure-functions was used, so I'm ...
- 2,459
1
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0
answers
98
views
What's in a Name? [closed]
StringReplacePart["StringReplacePart","At",{14,17}] ... Surely you can't be serious? ...
Naming Matters: I think what and how we call things is ...
- 6,076
0
votes
2
answers
54
views
How to make Mathematica to assemble components we already have like a regular input
Suppose we have the following list:
{5, 3}
I want to add the -> to the end of the first element in the list in Mathematica ...
- 313
0
votes
1
answer
137
views
Is this a bug in Total?
The output from the last of these lines doesn't make sense to me
Total[{}, {1}]
Total[{}, {1, 2}]
Total[{{1}, {1, 1}}, {2}]
Total[{}, {2}]
0
0
{1, 2}
0
The 3 ...
- 1,116
0
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0
answers
35
views
Create auto-completion for Wolfram Entity framework related functions when using with user-defined entity store
I am trying to create autocompletion for my custom entity store, for example in the document of EntityStore
...
- 21
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0
answers
43
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The command Total sums the entries of a list, is there a comparable command for the product of entries of a list? [duplicate]
I recently just found out about the command Total that gives the sum of a list. Was wondering whether there's an analogue that gives the product of the entries of a list? I see that there is the ...
- 2,335
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1
answer
495
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Keywords for the Wolfram Language [closed]
For a programming language, certain keywords are reserved; i.e., these tokens can't be used in any other context while programming in that particular language.
Here is a list of C language keywords ...
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