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. ë1.}
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
5ùarctest
¸
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
dx(f(x)))ñ+1 dx
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...}