HP HP-18C - Page 145

Multiplication and division before addition and subtraction. For
example, a
formula typed in as A +8 -;- C = 1 2 is interpreted as:
A
+
~ 12
C .
To divide the sum A + B by C, type the formula: (A +8) -;-C= 12 .
The T-bill formula can be written:
A
good rule is: when in doubt, use parentheses. So, if you were
unsure of how the T -bill formula written above would be inter-
preted, you
could type it as:
The extra parentheses don't change the meaning of the formula,
but they may make it easier to understand .
•
You cannot use parentheses for "implied" multiplication . For exam-
ple, a
formula printed in a book as P
sn
= P
s
(1- F) can be typed
into the solver as P::;t'l=PS> ~ ( 1-F). The x sign must be inserted
between PS and the parenthesis.
• You can use spaces to make the formula more readable as long as
there are no spaces inside variable names . The following version of
the T -bill formula is easier to read:
' r' I ELD
( (10000-PRICE) -;- PRICE) x
(36(1 -;- ~lATUR I TY)
• Formulas can use any of the functions listed in table 9-3 on page
144. Formulas can also include conditional expressions (covered on
page 148).
•
You cannot use logical operators (listed in table 9-4 on page 148) as
variable names. For example, you
cannot name a variable AND, but
CANDY and LAND are acceptable variable names .
9: The Formula Solver 143