Function definitions
on the HP48G
| sample: « ®
a b n « 'X' 'X' a b '(b-a)/n' EVAL SEQ »»
d: « DLIST »
mids: « 2 « a b '(a+b)/2' » DOSUBS »
sum: « SLIST »
S: « {{0}}SWAP + « ® s
t « s s s SIZE GET t + + »» STREAM »
VS: « OBJ ® ®
ARRY SWAP OBJ ® ®
ARRY 2 COL ® 'SDAT'
STO » |
Notice that functions d and sum have equivalent primitive
functions on this calculator. After storing the programs under the given
name (a directory is recommended), they appear on the VAR menu softkeys.
Users would press keys (with arguments on the stack) to create lists and
then store them under appropriate names: X, Y, DX, DY, XM, YM, etc.
One drawback is that the notation doesn't actually appear as on a computer
screen, for example, SY= S(ym*dx) is entered
with the keystrokes:
YM DX * S 'SY' STO
The PLOT menu choice of Type: Scatter will plot each point in
the matrix, SDAT. The program VS will take any
lists Y and X off the stack and store them in SDAT.
For example, to plot SY vs X enter keystrokes:
SY X VS PLOT ERASE
DRAW
To superimpose multiple graphs, simply omit ERASE. Connecting the points
is not an option. |
Arithmetic and scientific functions on
lists are applied to each element except for one bad inconsistency in the
+ key. Multiplication, for example, is entered with the keystrokes:
YM DX *
Indeed, entering 'EXP(-X)*SIN(2*X)'
EVAL will create a Y list for the stored variable X list. Unfortunately,
the + key joins or augments lists rather than adding componentwise. The
desired operation is ADD on the MTH LIST menu and an alternative is the
SEQ function to create tables. Ironically, an easy way to avoid this hassle
is to always subtract negatives;
'SIN(X^ 2 - -2*X
-
-3)' EVAL will work where 'SIN(X^2 + 2*X
+ 3)' fails. |
[Readers with browsers
that display fonts different to ours should note that
® is
intended to be a right pointing arrow, that «
is equivalent to << and »
to >> .]
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