Probability Functions - HP 39G User Manual

H I N T

Probability functions

COMB
!
PERM
RANDOM
Using mathematical functions
The results of POLYROOT will often not be easily seen in
HOME due to the number of decimal places, especially if they
are complex numbers. It is better to store the results of
POLYROOT to a matrix.
For example, POLYROOT([1,0,0,-8]
the three complex cube roots of 8 to matrix M1 as a complex
vector. Then you can see them easily by going to the Matrix
Catalog. and access them individually in calculations by
referring to M1(1), M1(2) etc.
Number of combinations (without regard to order) of n things
taken r at a time: n!/(r!(n r)).
COMB(n , r)
Example
COMB(5,2) returns 10. That is, there are ten different
ways that five things can be combined two at a time.
Factorial of a positive integer. For non-integers, ! = (x + 1).
This calculates the gamma function.
value!
Number of permutations (with regard to order) of n things
taken r at a time: n!/ (n-r)!.
PERM (n , r)
Example
PERM(5,2) returns 20. That is, there are 20 different
permutations of five things taken two at a time.
Random number (between zero and 1). Produced by a pseudo-
random number sequence. The algorithm used in the
RANDOM function uses a "seed" number to begin its
sequence. To ensure that two calculators must produce
different results for the RANDOM function, use the
RANDSEED function to seed different starting values before
using RANDOM to produce the numbers.
RANDOM
M1 will store
10-13