Math, Angle, and Test Operations 2-21
nPr (number of permutations) returns the number of
permutations of items taken number at a time. items and
number must be nonnegative integers. Both items and
number can be lists.
items nPr number
nCr (number of combinations) returns the number of
combinations of items taken number at a time. items and
number must be nonnegative integers. Both items and
number can be lists.
items nCr number
! (factorial) returns the factorial of either an integer or a
multiple of .5. For a list, it returns factorials for each
integer or multiple of .5. value must be ‚L.5 and 69.
value!
Note: The factorial is computed recursively using the relationship
(n+1)! = nän!, until n is reduced to either 0 or L1/2. At that point, the
definition 0!=1 or the definition (L1à2)!=‡p is used to complete the
calculation. Hence:
n!=nä(nN1)ä(nN2)ä ... ä2ä1, if n is an integer ‚0
n!= nä(nN1)ä(nN2)ä ... ä1à2ä‡p, if n+1à2 is an integer ‚0
n! is an error, if neither n nor n+1à2 is an integer ‚0.
(The variable n equals value in the syntax description above.)
nPr,
nCr
! (Factorial)