The
rules for evaluating
names
and
evaluating
programs
lead
to
one
of
the
fundamental
ideas in
programming
the
HP-28S. For this
dis-
cussion, "program"
means
a
program
storeq
in a variable,
and
"name
of a program"
means
the
name
of
the
variable
that
contains
a
program.
The
fundamental
idea is called structured
programming.
It
means
that
a
complicated task is
broken
into
subtasks,
and
a
program
is
written
for
each
sub
task.
The
main
program
can
now
be relatively simple, reflect-
ing
the
overall logic
of
the
task.
It
can
execute
each
subtask
simply
by
including
the
unquoted
name
of
the
program
for
that
subtask.
If
a
subtask
is
executed
more
than
once,
the
unquoted
name
can
be
in-
cluded
more
than
once.
If
other
main
programs
use
the
same
subtask,
they
can
execute
the
subtask
in
the
same
way.
Structured
programming
is
demonstrated
in
"Expanding
and
Collect-
ing Completely"
on
page
253, "Displaying a Binary Integer"
on
page
257,
and
"Median
of
Statistics Data"
on
page
270.
Evaluation
of
Aigebraics
Each algebraic is equivalent to a
program
that
contains only
unquoted
names
and
functions. Evaluating
an
algebraic
produces
the
same
re-
sult as evaluating
the
corresponding
program:
unquoted
names
are
evaluated,
and
functions
are executed. This topic is also discussed in
"Evaluation
of
Algebraic Objects" in
the
Reference
Manual.
The
result of evaluating a
name
depends
on
the
existence
of
a vari-
able with
that
name,
as described in "Evaluation of Global Names"
above.
Some
examples:
•
If
a
name
refers to a
user
function, you
can
use
the
user
function's
name
like a
built-in
function. Evaluation of
the
algebraic causes
execution of
the
user
function.
The
arguments
to
the
user
function,
enclosed in
parentheses
and
following
the
user
function's
name,
are
part
of
the
algebraic.
202
23:
Evaluation
To Next Page
Loading...
