Questions on expression testing and manipulation through pattern matching and constructing efficient patterns.

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8
votes
2answers
682 views

Mathematica rule substitution memory

First I present the specific programming question, and then I provide further background details. Given an expression in Mathematica, say f=3x+7y, there are two ...
7
votes
1answer
682 views

Extracting coefficients from a partial differential equation

Frequently, I come across the following problem: How to rewrite a complicated partial differential equation in a more clear way? I would like to create some order by collecting terms that are equal. ...
34
votes
9answers
1k views

Injecting a sequence of expressions into a held expression

Consider the following toy example: Hold[{1, 2, x}] /. x -> Sequence[3, 4] It will give Hold[{1, 2, Sequence[3, 4]}] ...
10
votes
3answers
779 views

Passing down arguments

In R, one can use ... to pass arguments down to another function. For example ...
43
votes
4answers
2k views

Using a PatternTest versus a Condition for pattern matching

My last question to the site resulted in several answers that involve using pattern matching in Mathematica, a feature I wasn't very familiar with at the time. I am currently reading Mathematica ...
19
votes
1answer
415 views

Why doesn't PatternTest work with Composition?

While playing around with the solutions to this question, I've found some very strange behaviour: ...
6
votes
3answers
321 views

Replacement rule only matches part of expression

I have the result of a calculation (which is too long to mention here) and it gives ...
8
votes
4answers
271 views

Check in a series if there exists adjacent values with less than a certain number of missing values

I'm working with a large number of series of different experiments, where there exist a lot of experiments where there are no entries. I now want to draw a sample where there should exist at least ...
19
votes
2answers
1k views

Pattern to match a non-empty list of non-empty lists

Is there a pattern to match a list of lists, containing at least one list, with each list containing at least one element? In the Mathematica documentation it says that the pattern ...
23
votes
2answers
430 views

How can I ensure that I am constructing patterns in the most efficient way possible?

Inspired by this answer, I am interested to know if there are best practices or rules of thumb for constructing patterns, for example for use in function definitions (...
46
votes
4answers
1k views