Texas Instruments TI-89 - Page 433

416 Appendix A: Functions and Instructions
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 416 of 132
ans()
2 ±
key
ans()
⇒
value
ans(
integer
)
⇒
value
Returns a previous answer from the
Home screen history area.
integer
, if included, specifies which previous
answer to recall. Valid range for
integer
is
from 1 to 99 and cannot be an expression.
Default is 1, the most recent answer.
To use
ans()
to generate the Fibonacci
sequence on the Home screen, press:
1
¸
1
1
¸
1
2
±
«
2
±
A
0
2
¸
2
¸
3
¸
5
approx()
MATH/Algebra menu
approx(
expression
)
⇒
value
Returns the evaluation of
expression
as a
decimal value, when possible, regardless of
the current
Exact/Approx
mode.
This is equivalent to entering
expression
and
pressing
¥ ¸
on the Home screen.
approx(p)
¸
3.141
...
approx(
list1
)
⇒
list
approx(
matrix1
)
⇒
matrix
Returns a list or matrix where each element
has been evaluated to a decimal value, when
possible.
approx({sin(p),cos(p)})
¸
{0.
ë
1.}
approx([‡(2),‡(3)])
¸
[1.414
...
1.732
...
]
Archive
CATALOG
Archive
var1
[,
var2
] [,
var3
] …
Moves the specified variables from RAM to
the user data archive memory.
You can access an archived variable the same
as you would a variable in RAM. However,
you cannot delete, rename, or store to an
archived variable because it is locked
automatically.
To unarchive variables, use
Unarchiv
.
10
!
arctest
¸
10
A
rc
h
ive arctest
¸
Done
5
ù
arctest
¸
50
1
5
!
arctest
¸
N
Unarc
h
iv arctest
¸
Done
1
5
!
arctest
¸
1
5
arcLen()
MATH/Calculus menu
arcLen(
expression1
,
var
,
start
,
end
)
⇒
expression
Returns the arc length of
expression1
from
start
to
end
with respect to variable
var
.
Regardless of the graphing mode, arc length
is calculated as an integral assuming a
function mode definition.
arcLen(cos(x),x,0,p)
¸
3.820
...
arcLen(f(x),x,a,b)
¸
⌡
⌠
a
b
(
d
d
x
(f(x)))
ñ
+1
d
x
arcLen(
list1,var,start,end
)
⇒
list
Returns a list of the arc lengths of each
element of
list1
from
start
to
end
with
respect to
var
.
arcLen({sin(x),cos(x)},x,0,p)
{3.820
...
3.820
...
}