37
votes
How can I adaptively simplify a curved shape?
We can use the Ramer-Douglas-Peucker algorithm to reduce the number of points. This algorithm was originally devised for processing map data.
...
- 233k
34
votes
Character to replace _ in symbol names?
This has been discussed on comp.soft-sys.math.mathematica. The gist is that there are lots of Unicode characters you could use, e.g. \[LetterSpace] or ...
- 8,744
27
votes
Why does removing a function and defining it on the same line not work?
Executing Trace on an expression reveals what is actually happening:
...
- 1,390
26
votes
How to make Mathematica variables declarative instead of just-in-time?
You are looking for $NewSymbol which is run every time a new symbol is created. For example, let say you only want x, ...
- 33.9k
19
votes
Accepted
How can I obtain a complete list of the kinds of atomic expressions in the Wolfram Language using only the language itself?
You can use EntityValue to find out what symbols can be atomic:
...
- 130k
16
votes
Accepted
When is a symbol a Symbol? Is there an easy Mathematica way to test if an object is a symbol sort of like a SymbolQ?
I'd probably use x_Symbol in a function argument to control evaluation. Otherwise, one might do the following (thanks to @Leonid for pointing out an oversight).
If ...
- 234k
14
votes
Why did Mathematica choose brackets for function arguments over parentheses?
Although Chip's answer already suffices to address the question, I would like to quote here a relevant part of the dialog by Theo Gray and Jerry Glynn in their book Exploring Mathematics with ...
14
votes
Accepted
How to make Mathematica variables declarative instead of just-in-time?
Edit: method extended for multiple contexts and unlocking mehtod added.
Let's protect whatever is a new symbol.
In old answer I've manually excluded symbols matching ...
Kuba♦
- 136k
13
votes
Generating list of alphabet letters
Nowadays, one can use Alphabet[] along with Take[] or Part[] + ...
13
votes
Character to replace _ in symbol names?
The issue is that Mathematica interprets underscore as Blank and interprets my_variable as a ...
- 4,321
13
votes
How can I define symbols but not have them show up in the front end?
Core Function
Here's a single function that does all this coloring stuff:
...
- 46.6k
13
votes
Accepted
Why does args symbol exist in a fresh kernel?
It's a type of otherwise harmless bug that tends to come and go with versions. I would suggest to report it to Wolfram, but also not to worry about it. Notice that the symbols have no associated ...
- 233k
13
votes
What does $ mean in an output?
This usually means you've exported a local symbol from the context in which it was localized. Consider:
Module[{x}, x]
(* x$24939 *)
Your results may vary. The <...
- 13.7k
12
votes
Bug: With[] pattern-variable renaming misses symbols within `Except`
I agree that this is a bug. However, I want to point out that this usage of Except does not seem to be allowed in older versions.
In version 9.0:
We don't get the ...
- 233k
12
votes
Accepted
Defining a symbol e that represents plus-minus-one, so that e^2 == 1 and e^3 == e
A quick way is to use TagSet[] and TagSetDelayed[] to teach Power[] how to deal with your ...
- 124k
12
votes
PlusMinus definition unexpectedly affects plotting
It appears that PlusMinus is the only wrapper that is not Protected:
...
- 270k
12
votes
When is a symbol a Symbol? Is there an easy Mathematica way to test if an object is a symbol sort of like a SymbolQ?
How about:
SymbolQ[_Symbol] = True
SymbolQ[_] = False
?
- 13.7k
12
votes
Accepted
Equivalent for \hookrightarrow, ↪
You can use an empty TemplateBox to create a new operator. For example:
...
- 130k
11
votes
How can I adaptively simplify a curved shape?
Here is my attempt to use ParametricPlot for obtaining an adaptive approximation of the shape. It is based on the code of glyph to ...
- 61.5k
11
votes
How can I adaptively simplify a curved shape?
Here I present a very simple angle-based polygon reduction algorithm as described in the chapter "A Simple Algorithm" of David Eberly's "Polyline Reduction". The only addition is ...
- 61.5k
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 ...
- 233k
11
votes
Accepted
How to list all user-defined symbols?
User defined symbols/functions are in the Global` context:
a = 1;
b[x_] := a x^2;
c[x_] := f[x];
Names["Global`*"]
{"a", "...
- 23.7k
11
votes
How can I implement a listener variable in Mathematica?
As part of handling this for myself I wrote a package that does it. The idea was to mimic the *Var() classes in tkinter. I'll do ...
- 46.6k
11
votes
Make symbols atomic, without losing their type
Perhaps what you want is symbolic tensors: http://reference.wolfram.com/language/tutorial/SymbolicTensors.html
...
- 233k
11
votes
Accepted
Make symbols atomic, without losing their type
You could use my TensorSimplify package help with this. Install the paclet with:
...
- 130k
11
votes
How to generate a horizontal histogram with words?
First of all, you don't need a Histogram, you need BarChart. Secondly, you need to massage the data slightly so each data point ...
- 65.8k
10
votes
Accepted
Why does removing a function and defining it on the same line not work?
I use the word internal symbol rather than just symbol, to make it easier to distinguish between the name of a symbol and the internal representation of the symbol inside the kernel. I felt I should ...
- 12.2k
10
votes
Accepted
Check if symbol is in core language
You can look it up using WolframLanguageData, which has a list of all pre-defined symbols:
...
- 70k
10
votes
Accepted
Change nested list of symbols to nested list of numbers
symbols = {e4, {e200, {e1, {e11, e23}}}};
Map[FromDigits@StringDrop[SymbolName[#], 1] &, symbols, {-1}]
{4, {200, {1, {11, 23}}}}
...
- 384k
10
votes
Accepted
Implement abstract algebraic structure
I decided it was worth giving another example of modern OOP in Mathematica. There will be a small amount of code, but almost all of it is boiler-plate. I use a package to handle most of the boiler ...
- 46.6k
Only top scored, non community-wiki answers of a minimum length are eligible