HP HP-28S - Defining New Functions

The functions MAXR (maximum real) and MINR (minimum real) return
symbolic constants for the largest and smallest positive real numbers
representable on the HP-28S. (To force a numerical result for a sym-
bolic constant, see HUsing 1['H on page 74.)
This section shows you how to use the function NEG. For conve-
nience, you can execute NEG by pressing [ CHS I (change sign) if no
command line is present. To enter the NEG command in the com-
mand line-for example, when you're keying in a program-press
NEG or [ill []] @].
Now negate the number in level 1 twice, once by pressing [ CHS I and
once by pressing NEG .
Negate the number in level 1.
ICHSI
3: -2. 06761537357E-13
2: 0
1: -2.46855006079
CIHImJIDlI:IIDaGIllmlGmm
Negate the number a second time.
NEG
3: -2. 06761537357E-13
2: 0
1: 2.46855006079
CIHImJIDlI:IIDaGIllmlGmm
Defining New Functions
You can create program variables that work like the built-in func-
tions-you can even use them in expressions. Such program variables,
called user functions, must fulfill two requirements:
• They must explicitly indicate their arguments .
• They must return exactly one result.
5: Real-Number Functions 79