HP 39gII, Руководство пользователя

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Using mathematical functions 179
Units and physical constants
When you press
b
, three menus become available:
•
the Math Functions menu (which appears by default)
•
the Units menu
•
the Physical Constants menu
The math functions menu is described extensively earlier
in this chapter.
Units
You can attach physical units to any numerical calculation
or result. A numerical value with units attached is referred
to as a measurement. You can operate on measurements
just as you do on numbers without units attached, except
that the units are carried along with the operations. The
function usimplify (unit simplify) will simplify the results
back to the simplest unit structure. The units are found in
the Units menu. Like the Math menu, the Units menu is
divided into a set of categories on the left and units in
each category on the right. The categories are:
Unit categories
Suppose you wish to add 20 centimeters and 5 inches.
1. If you want the result in
cm, start by entering the
20 cm.
20 b
\\
(to select
Length
)
>\ (to select
_cm
)
.
•
Length
•
Area
•
Volume
•
Time
•
Speed
•
Mass
•
Acceleration
•
Force
•
Energy
•
Power
•
Pressure
•
Temperature
•
Electricity
•
Light
•
Angle
•
Viscosity
•
Radiation