Section 6: Programming Basics
79
For example,
´b´A
becomes
´bA
,
´m´%
becomes
´m%
, and
O´#
becomes
O#
.
The removal of the
´
is not ambiguous because the
´
-shifted function
is the only logical one in these cases. The keycodes for such instructions do
not include the extraneous
´
even if you do key it in.
User Mode
User mode is a convenience to save keystrokes when addressing (calling
up) programs for execution. Pressing
´U
will exchange the primary
functions and
´
-shifted functions of the
A
through
E
keys only. In
User mode (
USER
annunciator displayed):
´
shift
Primary
A
B
C
D
E
¤
'
@
y
∕
|
shift
x
2
LN
LOG
Press
|
U
again to deactivate User mode.
Polynomial Expressions and Horner's Method
Some expressions, such as polynomials, use the same variable several times
for their solution. For example, the expression
f(x) = Ax
4
+ Bx
3
+ Cx
2
+ Dx + E
uses the variable
x
four different times. A program to solve such an
equation could repeatedly recall a stored copy of
x
from a storage register.
A shorter programming method, however, would be to use a stack which
has been filled with the constant (refer to Loading the Stack with a
Constant, page 41).
Horner's Method is a useful means of rearranging polynomial expressions to
cut calculation steps and calculation time. It is especially expedient in
_
and
f
, two rather long-running functions that use subroutines.
This method involves rewriting a polynomial expression in a nested fashion
to eliminate exponents greater than 1:
Ax
4
+ Bx
3
+ Cx
2
+
Dx + E
(
Ax
3
+
Bx
2
+ Cx + D
)
x + E
((
Ax
2
+ Bx + C
)
x + D
)
x + E
(((
Ax + B
)
x + C
)
x + D
)
x + E
Summary of Contents for HP-15C
Page 1: ...HP 15C Owner s Handbook HP Part Number 00015 90001 Edition 2 4 Sep 2011 ...
Page 17: ...Part l HP 15C Fundamentals ...
Page 64: ......
Page 65: ...Part ll HP 15C Programming ...
Page 118: ...118 ...
