Texas Instruments TITANIUM TI-89 - Manual (Page 792)

792 Appendix A: Functions and Instructions
Circle CATALOG
Circle x , y , r [, drawMode ]
Draws a circle with its center at window
coordinates (
x , y ) and with a radius of r .
x , y , and r must be real values.
If drawMode = 1, draws the circle (default).
If drawMode = 0, turns off the circle.
If drawMode = -1, inverts pixels along the circle.
Note: Regraphing erases all drawn items. See
also
PxlCrcl .
In a ZoomSqr viewing window:
ZoomSqr:Circle 1,2,3 ¸
ClockOff
CATALOG
ClockOff
Turns the clock OFF .
ClockOn CATALOG
ClockOn
Turns the clock ON .
ClrDraw
CATALOG
ClrDraw
Clears the Graph screen and resets the Smart
Graph feature so that the next time the Graph
screen is displayed, the graph will be redrawn.
While viewing the Graph screen, you can clear all
drawn items (such as lines and points) by
pressing † (
ReGraph ) or pressing 2 ˆ and
selecting 1:ClrDraw .
ClrErr CATALOG
ClrErr
Clears the error status. It sets errornum to zero
and clears the internal error context variables.
The Else clause of the Try...EndTry in the
program should use ClrErr or PassErr . If the
error is to be processed or ignored, use ClrErr . If
what to do with the error is not known, use
PassErr to send it to the next error handler. If
there are no more pending Try...EndTry error
handlers, the error dialog box will be displayed as
normal.
Note: See also PassErr and Try .
Program listing:
:clearerr()
:Prgm
:PlotsOff:FnOff:ZoomStd
:For i,0,238
:@xù i+xmin! xcord
: Try
: PtOn xcord,ln(xcord)
: Else
: If errornum=800 or
errornum=260 Then
: ClrErr ¦ clear the error
: Else
: PassErr ¦ pass on any other
error
: EndIf
: EndTry
:EndFor
:EndPrgm