Texas Instruments TI-89 Guide Book

Appendix A: Functions and Instructions 479
8992APPA.DOC TI-89 / TI-92 Plus: Appendix A (US English) Susan Gullord Revised: 02/23/01 1:48 PM Printed: 02/23/01 2:21 PM Page 479 of 132
The example Program Editor function to the
right uses
getType()
and
part()
to partially
implement symbolic differentiation. Studying
and completing this function can help teach
you how to differentiate manually. You could
even include functions that the
TI
-
89 / TI
-
92 Plus cannot differentiate, such
as Bessel functions.
:d(y,x)
:Func
:Loca
l
f
:If getType
(
y
)
="V
A
R"
: Return w
h
en
(
y=x,
1
,0,0
)
:If part
(
y
)
=0
: Return 0
¦
y=p,ˆ,
i
,numbers
:part
(
y,0
)
!
f
:If f="L"
¦
if negate
: Return
ë
d(
part
(
y,
1)
,x
)
:If f="
−
"
¦
if minus
: Return
d(
part
(
y,
1)
,x
)
ì
d(
part
(
y,2
)
,x
)
:If f="+"
: Return
d(
part
(
y,
1)
,x
)
+
d(
part
(
y,2
)
,x
)
:If f="
ù
"
: Return
part
(
y,
1)
ù
d(
part
(
y,2
)
,x
)
+part
(
y,2
)
ù
d(
part
(
y,
1)
,x
)
:If f="
{
"
: Return seq
(d(
part
(
y,
k)
,x
)
,
k
,
1
,part
(
y
))
:Return un
d
ef
:En
d
Func
PassErr
CATALOG
PassErr
Passes an error to the next level.
If “errornum” is zero,
PassErr
does not do
anything.
The
Else
clause in the program should use
ClrErr
or
PassErr
. If the error is to be
processed or ignored, use
ClrErr
. If what to
do with the error is not known, use
PassErr
to send it to the next error handler. (See also
ClrErr
.)
See
ClrErr
program listing example.
Pause
CATALOG
Pause
[
expression
]
Suspends program execution. If you include
expression
, displays
expression
on the Program
I/O screen.
expression
can include conversion operations
such as
4
DD
and
4
Rect
. You can also use the
4
operator to perform unit and number base
conversions.
If the result of
expression
is too big to fit on a
single screen, you can use the cursor pad to
scroll the display.
Program execution resumes when you
press
¸
.
Program segment:
©
:C
l
rIO
:De
l
Var temp
:1"temp[1]
:1"temp[2]
:Disp temp
[
2
]
:
¦
Guess t
h
e Pattern
:For i,3,20
: temp[i
ì
2]+temp[i
ì
1]"temp[i]
: Disp temp
[
i
]
: Disp temp,"Can you guess t
h
e
next","num
b
er?"
: Pause
:En
d
For
©

Texas Instruments TI-89 Specifications

General

Display size (HxV)	100 x 160 mm
Memory type	639K FLASH ROM, 188K bytes RAM
Compatible operating systems	Operating System 2.09
Battery type	AAA