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Appendix A: Functions and Instructions 419
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 419 of 132
cFactor()
MATH/Algebra/Complex menu
cFactor(
expression1
[
,
var
]
)
⇒
expression
cFactor(
list1
[
,var
]
)
⇒
list
cFactor(
matrix1
[
,var
]
)
⇒
matrix
cFactor(
expression1
)
returns
expression1
factored with respect to all of its variables
over a common denominator.
expression1
is factored as much as possible
toward linear rational factors even if this
introduces new non-real numbers. This
alternative is appropriate if you want
factorization with respect to more than one
variable.
cFactor(a^3
ù
x^2+a
ù
x^2+a^3+a)
¸
a
ø
(a
+
ë
i
)
ø
(a
+
i
)
ø
(x
+
ë
i
)
ø
(x
+
i
)
cFactor(x^2+4/9)
¸
(3
ø
x
+
ë
2
ø
i
)
ø
(3
ø
x
+
2
ø
i
)
9
cFactor(x^2+3)
¸
x
ñ
+
3
cFactor(x^2+a)
¸
x
ñ
+
a
cFactor(
expression1,var
)
returns
expression1
factored with respect to variable
var
.
expression1
is factored as much as possible
toward factors that are linear in
var
, with
perhaps non-real constants, even if it
introduces irrational constants or
subexpressions that are irrational in other
variables.
The factors and their terms are sorted with
var
as the main variable. Similar powers of
var
are collected in each factor. Include
var
if
factorization is needed with respect to only
that variable and you are willing to accept
irrational expressions in any other variables
to increase factorization with respect to
var
.
There might be some incidental factoring
with respect to other variables.
cFactor(a^3
ù
x^2+a
ù
x^2+a^3+a,x)
¸
a
ø
(a
ñ
+
1)
ø
(x
+
ë
i
)
ø
(x
+
i
)
cFactor(x^2+3,x)
¸
(x
+
‡3
ø
i
)
ø
(x
+
ë
‡3
ø
i
)
cFactor(x^2+a,x)
¸
(x
+
‡a
øë
i
)
ø
(x
+
‡a
ø
i
)
For the
AUTO
setting of the
Exact/Approx
mode, including
var
also permits
approximation with floating-point
coefficients where irrational coefficients
cannot be explicitly expressed concisely in
terms of the built-in functions. Even when
there is only one variable, including
var
might
yield more complete factorization.
Note: See also
factor()
.
cFactor(x^5+4x^4+5x^3
ì
6x
ì
3)
¸
x
5
+
4
ø
x
4
+
5
ø
x
3
ì
6
ø
x
ì
3
cFactor(ans(1),x)
¸
(
x
ì
.965
)
ø
(
x
+.6
1
2
)
ø
(
x
+
2.
1
3
)
ø
(x
+
1.11
ì
1.07
ø
i
)
ø
(x
+
1.11
+
1.07
ø
i
)
char()
MATH/String menu
char(
integer
)
⇒
character
Returns a character string containing the
character numbered
integer
from the
TI
-
89 / TI
-
92 Plus character set. See
Appendix B for a complete listing of
character codes.
The valid range for
integer
is 0–255.
char(38)
¸
"&"
char(65)
¸
"A"