Texas Instruments PLUS TI-89 - Manual (Page 439)

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^2ù (y^3ì y)+2468x
ù (y^2м 1)) ¸
1234ш xш (xш y + 2)ø (yс м 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+2i) ¸ 1 м 2ш i
conj([2,1ì 3i;ë i,л 7]) ¸



 2 1+3ш i
i ë 7
conj(z) z
conj(x+iy) x + ë iø 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