Texas Instruments Titanium TI-89, User Manual

Page: 775 / 977

772 Appendix A: Functions and Instructions
comDenom(
expression1,var
)
returns a reduced ratio of
numerator and denominator expanded with respect to
var
. The terms and their factors are sorted with
var
as
the main variable. Similar powers of
var
are collected.
There might be some incidental factoring of the
collected coefficients. Compared to omitting
var
, this
often saves time, memory, and screen space, while
making the expression more comprehensible. It also
makes subsequent operations on the result faster and
less likely to exhaust memory.
comDenom((y^2+y)/(x+1)
^2+y^2+y,x)
¸
comDenom((y^2+y)/(x+1)
^2+y^2+y,y)
¸
If
var
does not occur in
expression1
,
comDenom( expression1,var )
returns a reduced ratio of
an unexpanded numerator over an unexpanded
denominator. Such results usually save even more
time, memory, and screen space. Such partially
factored results also make subsequent operations on
the result much faster and much less likely to exhaust
memory.
comDenom(exprn,abc)
!
comden
(exprn)
¸
Done
comden((y^2+y)/(x+1)^2+y^2+y)
¸
Even when there is no denominator, the
comden
function is often a fast way to achieve partial
factorization if
factor()
is too slow or if it exhausts
memory.
Hint : Enter this
comden()
function definition and
routinely try it as an alternative to
comDenom()
and
factor()
.
comden(1234x^2
ù
(y^3
ì
y)+2468x
ù
(y^2
ì
1))
¸
1234
ø
x
ø
(x
ø
y + 2)
ø
(y
ñ ì
1)
conj()
MATH/Complex menu
conj(
expression1
)
⇒
expression
conj(
list1
)
⇒
list
conj(
matrix1
)
⇒
matrix
Returns the complex conjugate of the argument.
Note: All undefined variables are treated as real
variables.
conj(1+2
i
)
¸
1
ì
2
ø i
conj([2,1
ì
3 i ;
ë
i ,
ë
7])
¸




2 1+3
ø
i
i
ë 7
conj(z) z
conj(x+ i y) x + ë i ø y
CopyVar
CATALOG
CopyVar
var1
,
var2
Copies the contents of variable
var1
to
var2.
If
var2
does not exist,
CopyVar
creates it.
Note:
CopyVar
is similar to the store instruction
(
!
) when you are copying an expression, list,
matrix, or character string except that no
simplification takes place when using
CopyVar
.
You must use
CopyVar
with non-algebraic variable
types such as Pic and GDB variables.
x+y ! a ¸ x + y
10
!
x
¸
10
CopyVar a,b
¸
Done
a
!
c
¸
y + 10
DelVar x
¸
Done
b ¸ x + y
c ¸ y + 10