Texas Instruments PLUS TI-89 - Manual (Page 502)

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 л 14 щ 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… л.816…
.861… л.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