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Appendix A: Functions and Instructions 485
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 485 of 132
PxlText
CATALOG
PxlText
string
,
row
,
col
Displays the Graph screen and places
character string
string
on the screen, starting
at pixel coordinates (
row
,
col
).
string
is positioned with the upper-left corner
of its first character at the coordinates.
Note: Regraphing erases all drawn items.
TI-89:
PxlText "sample
text",20,10
¸
TI-92 Plus:
PxlText "sample
text",20,50
¸
PxlVert
CATALOG
PxlVert
col
[
,
drawMode
]
Draws a vertical line down the screen at pixel
position
col
.
If
drawMode
= 1, draws the line (default).
If
drawMode
= 0, turns off the line.
If
drawMode
= -1, turns a line that is on to off
or off to on (inverts pixels along the line).
Note: Regraphing erases all drawn items. See
also
LineVert
.
PxlVert 50,1
¸
QR
MATH/Matrix menu
QR
matrix
,
qMatName
,
rMatName
[
,
tol
]
Calculates the Householder QR factorization
of a real or complex
matrix
. The resulting Q
and R matrices are stored to the specified
MatNames
. The Q matrix is unitary. The R
matrix is upper triangular.
Optionally, any matrix element is treated as
zero if its absolute value is less than
tol
. This
tolerance is used only if the matrix has
floating-point entries and does not contain
any symbolic variables that have not been
assigned a value. Otherwise,
tol
is ignored.
•
If you use
¥¸
or set the mode to
Exact/Approx=APPROXIMATE
, computations
are done using floating-point arithmetic.
•
If
tol
is omitted or not used, the default
tolerance is calculated as:
5
E
ë
14
ù
max(dim(
matrix
))
ù
rowNorm(
matrix
)
The floating-point number (9.) in
m1
causes results to be calculated in floating-
point form.
[1,2,3;4,5,6;7,8,9.]
!
m1
¸
1
2 3
4 5 6
7 8 9.
QR m1,qm,rm
¸
Done
qm
¸
.123… .904… .408…
.492… .301…
ë
.816…
.861…
ë
.301… .408…
rm
¸
8.124… 9.601… 11.078…
0. .904… 1.809…
0. 0. 0.
[m,n;o,p]
!
m1
¸
[]
m n
o p