HP 40gs User Manual page 265

hp40g+.book Page 13 Friday, December 9, 2005 1:03 AM
How to enter infix
functions
How to enter prefix
functions
Equation Writer
select the entire expression and press
obtain:
However, if you type:
∞
∑
= 1
K
select the entire expression and press
obtain 1.
An infix function is one that is typed between its
arguments. For example, AND, |and MOD are infix
functions.You can either:
•
type them in Alpha mode and then enter their
arguments, or
•
select them from a CAS menu or by pressing an
appropriate key, provided that you have already
written and selected the first argument.
You move from one argument to the other by pressing
and . The comma enables you to write a
complex number: when you type (1,2), the
parentheses are automatically placed when you type
the comma. If you want to type (–1,2), you must
select –1 before you type the comma.
A prefix function is one that is typed before its arguments.
To enter a prefix function, you can:
•
type the first argument, select it, then select the
function from a menu, or
•
you can select the function from a menu, or by
directly entering it in Alpha mode, and then type the
arguments.
The following example illustrates the various ways of
entering a prefix function. Suppose you want to factor the
2
expression x – 4, then find its value for x = 4. FACTOR is
the function for factoring, and it is found on the
menu. SUBST is the function for substituting a value for a
variable in an expression, and it is also found in the
menu.
l
, you
4
-- -
5
1
------------------------- -
⋅ ( )
K K + 1
, you
15-13