Texas Instruments TI-89 Manual Book page 507

ref()
MATH/Matrix menu
ref(matrix1[, tol])
Returns the row echelon form of
Optionally, any matrix element is treated as
zero if its absolute value is less than
tolerance is used only if the matrix has
floating-point entries and does not contain
any symbolic variables that have not been
assigned a value. Otherwise,
If you use ¥ ¸ or set the mode to
Exact/Approx=APPROXIMATE
are done using floating-point arithmetic.
If is omitted or not used, the default
tol
tolerance is calculated as:
ë 14 ù max(dim(matrix1))
5
E
ù rowNorm(matrix1)
Note: See also
remain()
MATH/Number menu
remain(expression1, expression2)
remain(list1, list2)
remain(matrix1, matrix2)
Returns the remainder of the first argument
with respect to the second argument as
defined by the identities:
remain(x,0)  x
remain(x,y)  xì yùiPart(x/y)
As a consequence, note that
ì
remain(x,y)
has the same sign as the first argument.
Note: See also
Rename
CATALOG
Rename oldVarName, newVarName
Renames the variable
newVarName
Request
CATALOG
Request promptString, var
If
Request
construct, it creates an input box for the user
to type in data. If it is a stand-alone
instruction, it creates a dialog box for this
input. In either case, if
is displayed and highlighted in the input box
as a default choice.
characters.
This instruction can be stand-alone or part of
a dialog construct.
490 Appendix A: Functions and Instructions
matrix
matrix1
is ignored.
tol
, computations
rref().
expression
list
matrix
remain(ì x,y)
. The result is either zero or it
.
mod()
as
oldVarName
.
is inside a ...
Dialog EndDlog
contains a string, it
var
must be { 20
promptString
ref([ë 2,ë 2,0,ë 6;1,ë 1,9,ë 9;ë 5,
2,4,ë 4]) ¸
.
. This
tol
[a,b,c;e,f,g]!m1 ¸
ref(m1) ¸
remain(7,0) ¸
remain(7,3) ¸
remain(ë 7,3) ¸
remain(7,ë 3) ¸
remain(ë 7,ë 3) ¸
remain({12,ë 14,16},{9,7,ë 5})
¸
 remain([9,ë 7;6,4],[4,3;4,ë 3])
¸
{1,2,3,4}! L1 ¸
Rename L1, list1 ¸
list1 ¸
Request "Enter Your Name",str1
¸
1 ë 2/5 ë 4/5 4/5
0 1 4/7 11/7
ë 62/71
0 0 1
a b
[
e f
f g
1
e e
aøgì cøe
0 1
aøfì bøe
{3
1
[
2
{1,2,3,4}
{1,2,3,4}
c
]
g
7
1
ë 1
1
ë 1
0 1}
ë 1
]
1
Done