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422 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 422 of 132
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
ñì
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
1
0
!
x
¸
1
0
CopyVar a,
b
¸
Done
a
!
c
¸
y
+
1
0
De
l
Var x
¸
Done
b
¸
x
+
y
c
¸
y
+
1
0