HP -11C Owner's Handbook Manual page 28

§2 Section 3; Numeric Functions
Rectangular Conversion. Press-
ing {f) (rectangular) converts
values in the X- and Y-registers
representing polar coordinates (mag-
nitude r, angle @), to rectangular
coordinates (x, y).
Example :
To Convert Keystrokes Display
Rectangular coordinates
to polar:
y 5 5.0000
x 10 10
r WI?) 11.1803
0 ey) 26.5651
Polar coordinates to
rectangular:
8 30 (ENTER 30.0000
r 12 12
x (+R) 10.3923
y x=) 6.0000
1.
Probability
Permutation. Pressing [f)[Py.x) calculates the number of possible
arrangements of y different items taken in quantities of x items at
a time, where different orders of the same x items are counted
separately. (No item occurs more than once in an arrangement.)
calculates permutations by the following formula:
~ ~V~
Section 3: Numeric Functions 53
Combination. Pressing (9) calculates the number of
possible sets of y different items taken in quantities of x items at a
time regardless of order (where no item occurs more than once in a
set). (C);x} calculates combinations by the following formula:
y!
*e xy —x)!
To execute a permutation or combination:
1. Key in the number of items (y).
2. Press [ENTER].
3. Key in the quantity of items required (x) per arrangement or
set.
4. Press (A[Pe.xJor @)[Crx).
eae]
Keys > (Pex
or (9 )[Cyx] LAST X
The result, p or c, will appear in the displayed X-register, the stack
will drop, and the quantity per arrangement or set (x) is placed in
the LAST X register.
All permutation and combination inputs must be non-
negative integers.
Note: The execution times for and calculations
can be several seconds or longer, depending on the
magnitude of your y and x inputs. The maximum value you
can input for a [Py,x] or [€y.x) calculation is 10'° — 1, The
running message will flash in the display during execution of
Py.x)and (Cx,x]catculations.