| 
   Home Manual Packages Global Index Keywords Quick Reference
   | 
  1.1.2 Invoking a procedure 
A Yorick function which has side effects may sensibly be invoked as a
procedure, discarding the value returned by the function, if any:
 
 |  | plg, sin(theta)*exp(-theta/6), theta
write, file, theta, sin(theta)*exp(-theta/6)
close, file
 | 
 
The plg function plots a graph on your screen -- in this case,
three cycles of a damped sine wave.  The graph is made by connecting
200 closely spaced points by straight lines. 
The write function writes a two column, 200 line table of values
of the same damped sine wave to the file `damped.txt'.  Then
close closes the file, making it unavailable for any further
write operations. 
A line which ends with a comma will be continued, to allow procedures
with long argument lists.  For example, the write statement could
have been written: 
 |  | write, file, theta,
             sin(theta)*exp(-theta/6)
 | 
 
A procedure may be invoked with zero arguments; several graphics
functions are often used in this way:
 
 
The hcp function writes the current graphics window contents to
a "hardcopy file" for later retrieval or printing.  The fma
function stands for "frame advance" -- subsequent plotting commands
will draw on a fresh page.  Normally, plotting commands such as
plg draw on top of whatever has been drawn since the previous
fma. 
 
 |