Cfactor(), Char(), Checktmr() – Texas Instruments TITANIUM TI-89 User Manual
Page 791: Appendix a: functions and instructions 791
Appendix A: Functions and Instructions
791
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^3ùx^2+aùx^2+a^3+a)
¸
aø(a
+
ë
i
)ø(a
+
i
)ø(x
+
ë
i
)ø(x
+
i
)
cFactor(x^2+4/9)
¸
(3шx + л2ш
i
)ø(3шx + 2ш
i
)
9
cFactor(x^2+3)
¸
xñ
+
3
cFactor(x^2+a)
¸
xñ
+
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^3ùx^2+aùx^2+a^3+a,x)
¸
aø(aс
+
1)ш(x
+
ë
i
)ø(x
+
i
)
cFactor(x^2+3,x)
¸
(x
+
‡
3ø
i
)ø(x
+
л
‡
3ш
i
)
cFactor(x^2+a,x)
¸
(x
+
‡
aøë
i
)ø(x
+
‡
aø
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^3ì6xì3)
¸
x
5
+
4øx
4
+
5шx
3
м
6шxм3
cFactor(ans(1),x)
¸
(x
м
.965)ш(x
+.612)ø(x
+
2.13)ø
(x
+
1.11
м
1.07ш
i
)ø
(x
+
1.11
+
1.07ø
i
)
char()
MATH/String menu
char(
integer
)
⇒
⇒
⇒
⇒
character
Returns a character string containing the
character numbered
integer
from the
TI-89 Titanium/Voyage™ 200 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"
checkTmr()
CATALOG
checkTmr(
starttime
)
⇒
⇒
⇒
⇒
integer
Returns an integer representing the number of
seconds that have elapsed since a timer was
started.
starttime
is an integer returned from the
startTmr()
function.
You can also use a list or matrix of
starttime
integers. Valid
starttime
integers must fall
between 0 and the current time of the clock. You
can run multiple timers simultaneously.
Note: See also
startTmr()
and
timeCnv()
.
startTmr()
¸
148083315
checkTmr(148083315) 34
startTmr()!Timer1
©
startTmr()!Timer2
©
checkTmr(Timer1)!Timer1Value
©
checkTmr(Timer2)!Timer2Value