Programming 18-19
IFERR...THEN...ELSE…END allows a program to intercept 
error conditions that otherwise would cause the program 
to abort. Its syntax is:
IFERR trap-clause
THEN clause_1 
ELSE clause_2 
END :
Example
IFERR
60/X 
 Y:
THEN
MSGBOX "Error: X is zero.":
ELSE
MSGBOX "Value is "Y:
END:
RUN Runs the named program. If your program name contains 
special characters, such as a space, then you must 
enclose the file name in double quotes (" ").
RUN "program name": or RUN programname:
STOP Stops the current program.
STOP:
Drawing commands
The drawing commands act on the display. The scale of 
the display depends on the current aplet's Xmin, Xmax, 
Ymin, and Ymax values. The following examples assume 
the hp 39gs default settings with the Function aplet as the 
current aplet.
ARC Draws a circular arc, of given radius, whose centre is at 
(x,y) The arc is drawn from start_angle_measurement, to 
end_angle_measurement.
ARC x;y;radius;start_angle_measurement ;
end_angle_measurement:
HP 39gs English.book  Page 19  Wednesday, December 7, 2005  11:24 PM