HP 39gII, User Manual

Page: 182 / 355

172 Using mathematical functions
H I N T
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] M1
will
store the three complex cube roots of 8 to matrix M1 as
a complex vector. Then you can see them by going to the
Matrix Catalog. You can also access them individually in
calculations by referring to M1(1), M1(2) etc.
Probability functions
COMB
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, ! =
Γ
(x +
1)
. This calculates the gamma function.
value!
Example:
5! Returns
120
PERM
Number of permutations (with regard to order) of n things
taken r at a time:
n!/(r!(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.