`cputime', `tstart', `tstop'
----------------------------

cputime(ONOFF)
     :: Stop displaying `cputime' if its argument is 0, otherwise start
     displaying `cputime' after every top level evaluation of Asir
     command.

tstart()
     :: Resets and starts timer for CPU time and GC time.

tstop()
     :: Stops timer and then displays CPU time GC time elapsed from the
     last time when timer was started.

RETURN
     0

ONOFF
     flag (arbitrary)

   * Command `cputime()' with NON-ZERO argument enables Asir to display
     CPU time and GC time after every evaluation of top level Asir
     command.  The command with argument 0 disables displaying them.

   * Command `tstart()' starts measuring CPU time and GC time without
     arguments.  The parentheses `()' may be omitted.

   * Command `tstop()' stops measuring CPU time and GC time and displays
     them without arguments. The parentheses `()' may be omitted.

   * Command `cputime(ONOFF)' has same meaning as
     `ctrl("cputime",ONOFF)'.

   * Nested use of `tstart()' and `tstop()' is not expected.  If such
     an effect is desired, use `time()'.

   * On and off states by `cputime()' have effects only to displaying
     mode.  Time for evaluation of every top level statement is always
     measured.  Therefore, even after a computation has already started,
     you can let Asir display the timings, whenever you enter the
     debug-mode and execute `cputime(1)'.

     [49] tstart$
     [50] fctr(x^10-y^10);
     [[1,1],[x+y,1],[x^4-y*x^3+y^2*x^2-y^3*x+y^4,1],[x-y,1],
     [x^4+y*x^3+y^2*x^2+y^3*x+y^4,1]]
     [51] tstop$
     80msec + gc : 40msec

References
     *Note `time': time, *Note `ctrl': ctrl.

