HP -11C Owner's Handbook Manual page 24

44 Section 3: Numeric Functions
2. Gamma Function.
The key can also be used to calculate the Gamma
function, denoted by I(x), which occurs in certain problems
in advanced mathematics and statistics.* Pressing [x1] gives
you [(x + 1). To calculate the Gamma function of a number,
subtract 1 from the number. Then, with the result in the
displayed X-register, press [f)[x1].
Square Root. Pressing [V3] calculates the square root of the
number in the displayed X-register.
Squaring. Pressing [@]{x") calculates the square of the number in
the displayed X-register.
Keystroke . .
To Calculate Example Display
Reciprocal 25 25
Tx 0.0400
Factorial 8 8
le 40,320.0000
Gamma 27 2.7
ENTER) 1 1.7000 j
ice) 1.5447
Square Root 3.9 3.9
Wa 1.9748
Square 12.3 12.3
i) 151.2900
i}
* ( i ) can be used for both the Factorial and Gamma functions because when x is a
nonnegative integer n, I(x +1) = I(n +1) =n!. The Gamma function can be regarded as a
generalization of the factorial function, since the number in the X-register is not limited
to nonnegative integers. Conversely, the factorial function can be regarded as a special
case of the Gamma function.
~~
Section 3: Numeric Functions 45
Trigonometric Operations
The six basic trigonometric functions operate in the trigonometric
mode you select.
Trigonometric Modes. Selecting a specific trig mode does not
convert any number already in the calculator to that mode.
Selecting a specific trig mode is simply telling the calculator what
unit of measure (degree, radian, or grad) to use when executing a
trig function.
Pressing [9] selects the Degree trig mode. No annunciator
appears in the display.
Pressing (9 ][RAD] selects the Radian trig mode. While [RAD] mode is
set, the RAD annunciator appears in the display.
(@)(RAD) 0.0000
0
Pressing [9] [GRD] selects the Grad trig mode. While [GRO] mode is
set, the GRAD annunciator appears in the display.
- 9.0000
(a(R
The calculator is always set to one of the three trig modes.
Continuous Memory maintains the last trig mode selected, even
when the calculator is turned off, then on again. If a power loss
occurs, or if you reset Continuous Memory (refer to page 20), the
calculator will automatically reset to (DEG) mode.
Trigonometric Functions.
Calculates
sine
arc sine
cosine
arc cosine
tangent
arc tangent