Difference between revisions of "User:Saul/algebra"
From Organic Design wiki
m (→Combinations/Choose) |
(→Combinations and Permutations) |
||
Line 2: | Line 2: | ||
=== Permutations/Pick === | === Permutations/Pick === | ||
A permutation is a sequence where the order does matter.<br> | A permutation is a sequence where the order does matter.<br> | ||
− | This is often notated by '''n pick r''' where '''n''' is the data set - say 40 lotto balls and '''r''' is the selection count - say 8 balls. | + | This is often notated by '''n pick r''' where '''n''' is the data set - say 40 lotto balls and '''r''' is the selection count - say 8 balls.<br> |
+ | The general formulae for permutations is:<br> | ||
+ | '''P = n! / (n-k)!''' | ||
=== Combinations/Choose === | === Combinations/Choose === | ||
A combination is a sequence where the order does NOT matter.<br> | A combination is a sequence where the order does NOT matter.<br> | ||
− | This is often notated by '''n choose r''' - '''n''' and '''r''' mean the same thing as in pick. | + | This is often notated by '''n choose r''' - '''n''' and '''r''' mean the same thing as in pick.<br> |
+ | The general formulae for combinations is:<br> | ||
+ | '''C = n! / ((n-k)!k!)'''<br> | ||
+ | Also note that:<br> | ||
+ | '''n choose k''' is the same as '''n choose (n - k)''' |
Revision as of 03:24, 25 September 2019
Combinations and Permutations
Permutations/Pick
A permutation is a sequence where the order does matter.
This is often notated by n pick r where n is the data set - say 40 lotto balls and r is the selection count - say 8 balls.
The general formulae for permutations is:
P = n! / (n-k)!
Combinations/Choose
A combination is a sequence where the order does NOT matter.
This is often notated by n choose r - n and r mean the same thing as in pick.
The general formulae for combinations is:
C = n! / ((n-k)!k!)
Also note that:
n choose k is the same as n choose (n - k)