Texas Instruments TI-89 - Page 465

448 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 448 of 132
factor(rationalNumber)
returns the rational
number factored into primes. For composite
numbers, the computing time grows
exponentially with the number of digits in the
second-largest factor. For example, factoring
a 30-digit integer could take more than a day,
and factoring a 100-digit number could take
more than a century.
Note: To stop (break) a computation, press
´
.
If you merely want to determine if a number
is prime, use
isPrime()
instead. It is much
faster, particularly if
rationalNumber
is not
prime and if the second-largest factor has
more than five digits.
factor(152417172689)
¸
1
23457
ø
1
234577
isPrime(152417172689)
¸
false
Fill
MATH/Matrix menu
Fill expression, matrixVar
⇒
matrix
Replaces each element in variable
matrixVar
with
expression
.
matrixVar
must already exist.
[1,2;3,4]
!
amatrx
¸
[
1 2
3 4
]
Fi
ll
1
.0
1
,amatrx
¸
Done
amatrx
¸
[
1
.0
1
1
.0
1
1.01 1.01
]
Fill expression, listVar
⇒
list
Replaces each element in variable
listVar
with
expression
.
listVar
must already exist.
{1,2,3,4,5}
!
alist
¸
{1 2 3 4 5}
Fill 1.01,alist
¸
Done
alist
¸
{1.01 1.01 1.01 1.01 1.01}
floor()
MATH/Number menu
floor(expression)
⇒
integer
Returns the greatest integer that is

the
argument. This function is identical to
int()
.
The argument can be a real or a complex
number.
floor(
ë
2.14)
¸ ë
3.
floor(list1)
⇒
list
floor(matrix1)
⇒
matrix
Returns a list or matrix of the floor of each
element.
Note: See also
ceiling()
and
int()
.
floor({3/2,0,
ë
5.3})
¸
{1 0
ë
6.}
floor([1.2,3.4;2.5,4.8])
¸
[
1. 3.
2. 4.
]
fMax()
MATH/Calculus menu
fMax(expression, var)
⇒
Boolean expression
Returns a Boolean expression specifying
candidate values of
var
that maximize
expression
or locate its least upper bound.
fMax(1
ì
(x
ì
a)^2
ì
(x
ì
b)^2,x)
¸
x =
a+b
2
fMax(.5x^3
ì
x
ì
2,x)
¸
x = ˆ