Notes For Algebraic Calculator Users - HP -28S Manual

Notes for Algebraic
Calculator Users
c
Many calculators, including the great majority of simple, "four-func-
tion" calculators, use variations of the
algebraic
calculator interface.
The name derives from the feature that the keystroke sequences used
for simple calculations closely parallel the way in which the calcula-
tion is specified in algebraic expressions "on paper." That is, to
evaluate 1
+
2 - 3, you press
OJ G
[l]
G
rn
G·
This interface works nicely for expressions containing numbers and
operators-functions
like
+, -,
x, and / that are written in infix
notation between their arguments. More sophisticated calculators al-
low you to enter parentheses to specify precedence (the order of
operations). However, the introduction of prefix functions, like SIN,
LOG, and so on, leads to two different variations:
• Ordinary algebraic calculators use a combination of styles-infix
operators remain infix, but prefix functions are entered in a postfix
style (like RPN calculators). For example, 1
+
SIN(23) is entered as
OJ
G
[l]
rn
[]!ill
G·
This approach has the advantages of being
able to show intermediate results, and of preserving single-key
evaluations of prefix functions (that is, without parentheses), but
the disadvantage of losing the correspondence with ordinary math-
ematical notation that is the primary advantage of the algebraic
interface.
302 C: Notes for Algebraic Calculator Users