Texas Instruments TI-89 Manual Book page 495

By combining the variations of
extract all of the sub-expressions in the
simplified result of
the example to the right, you can store an
argument or operand and then use
extract further sub-expressions.
Note: When using
particular order in sums and products.
Expressions such as (x+y+z) and (xì yì z)
are represented internally as (x+y)+z and
(xì y)ì z. This affects the values returned for
the first and second argument. There are
technical reasons why
y+x instead of x+y.
Similarly, xù yù z is represented internally as
(xù y)ù z. Again, there are technical reasons
why the first argument is returned as yøx
instead of xøy.
When you extract sub-expressions from a
matrix, remember that matrices are stored as
lists of lists, as illustrated in the example to
the right.
478 Appendix A: Functions and Instructions
part() , you can
. As shown in
expression1
to
part()
, do not rely on any
part()
x+y+z,1 returns
part( )
part(cos(pù x+3)) ¸
part(cos(pù x+3),0) ¸
part(cos(pù x+3),1)! temp ¸
temp ¸
part(temp,0) ¸
part(temp) ¸
part(temp,2) ¸
part(temp,1)! temp ¸
part(temp,0) ¸
part(temp) ¸
part(temp,1) ¸
part(temp,2) ¸
part(x+y+z) ¸
part(x+y+z,2) ¸
part(x+y+z,1) ¸
part(xù yù z) ¸
part(xù yù z,2) ¸
part(xù yù z,1) ¸
part([a,b,c;x,y,z],0) ¸
part([a,b,c;x,y,z]) ¸
part([a,b,c;x,y,z],2)! temp
¸
part(temp,0) ¸
part(temp) ¸
part(temp,3) ¸
delVar temp ¸
1
"cos"
3+pøx
pøx+3
"+"
2
3
pøx
"ù "
2
p
x
2
z
y+x
2
z
yøx
"{"
2
{x y z}
"{"
3
z
Done