Texas Instruments TI-89 User Manual - Page 792

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 Program listing: 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. :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 792 Appendix A: Functions and Instructions