Math Extensions

Math extensions for .NET is a library with useful methods doing recurring mathematical, stastical and analysis operations. There are methods for combinatorics and sequence analysis, generation and manipulation.

Combinatorics

Assume we have this string:

var source = "abc";

We can use the Combine, PartialPermute and Permute methods to obtain the following results:

Combine

In this example we get combinations of the string "abc" taken at groups of 2 without repetition. Remember that elements' order doesn't matter, when speaking of combinations.

var result = source.Combine(2, GenerateOptions.WithoutRepetition);

Output:
ab
ac
bc

PartialPermute

In this example we get partial permutations of the string "abc" taken at groups of 2 without repetition. In this case order does matter.

var result = source.PartialPermute(2, GenerateOptions.WithoutRepetition);

Output:
ab
ac
ba
ca
cb

Permute

In this example we get permutations of the string "abc" without repetition.

var result = source.Permute(GenerateOptions.WithoutRepetition);

Output:
abc
acb
bac
cab
cba

Sequence Analysis

FindSequenceKind

This method analyze a sequence and returns the sequence kind if a pattern is found.

var sequenceA = new[] { 2, 4, 6, 8, 10 };
var sequenceB = new[] { 3, 9, 27, 81 };
var thisIsAmbiguous = new[] { 2, 4 };

Console.WriteLine(sequenceA.FindSequenceKind());
Console.WriteLine(sequenceB.FindSequenceKind());
Console.WriteLine(thisIsAmbiguous.FindSequenceKind());

Output:
Arithmetic
Geometric
Indeterminable

Sequence Generation

Arithmetic

This method generates an arithmetic sequence between the specified lower and upper limits, given an additive constant.

var arithmeticSequence = SequenceGeneration.Arithmetic(5, 5, 50);

Output:
5
10
15
20
25
30
35
40
45
50

Fibonacci

This method generates Fibonacci numbers between the specified lower and upper limits. In this example we generate Fibonacci numbers between 10 and 1000:

var fibonacci = SequenceGeneration.Fibonacci(10, 1000);

Output:
13
21
34
55
89
144
233
377
610
987

Geometric

This method generates a geometric sequence between the specified lower and upper limits, given a multiplicative constant.

var geometricSequence = SequenceGeneration.Geometric(2, maxValue: 64);

Output:
1
2
4
8
16
32
64

PrimeNumbers

This method generates a prime numbers sequence between the specified lower and upper limits, using a Sieve of Eratosthenes based algorithm.

var primeNumbers = SequenceGeneration.PrimeNumbers(maxValue: 50);

Output:
2
3
5
7
11
13
17
19
23
29
31
37
41
43
49

Triangular

This method generates a triangular sequence between the specified lower and upper limits.

var triangularSequence = SequenceGeneration.Triangular(maxValue: 20);

Output:
1
3
6
10
15

Others IEnumerable extensions

RandomOrDefault

As you can expect, this method returns a random element from a list or default(T) if the list is empty.

Shuffle

This method returns the same list with elements' order randomized.

TakeRandom

Works as Take but the elements are taken randomly instead of orderly.

TakeRandomWhile

Same here, works as TakeWhile but elements are taken randomly instead of orderly.

License

Math Extensions is released under MIT License.