====== "freeze, unfreeze" commands ======

===== Purpose =====

"Freeze" to a point in time.  Remember circuit voltages and currents. 

===== Syntax =====

  freeze
  unfreeze

===== Comments =====

After the freeze command, the transient and fourier analysis will continue from the values that were kept by the freeze command, instead of progressing every time.
 
This allows reruns from the same starting point, which may be at any time, not necessarily 0. 

===== Examples =====

  transient 0 1 .01
A transient analysis starting at zero, running until 1 second, with step size .01 seconds. After this run, the clock is at 1 second.
  freeze
Remember the time, voltages, currents, etc.
  transient
Another transient analysis. It continues from 1 second, to 2 seconds. (It spans 1 second, as before.) This command was not affected by the freeze command.
  transient
This will do exactly the same as the last one. From 1 second to 2 seconds. If it were not for freeze, it would have started from 2 seconds.
  transient 1.5 .001
Try again with smaller steps. Again, it starts at 1 second.
  unfreeze
Release the effect of freeze.
  transient
Exactly the same as the last time, as if we didn't unfreeze. (1 to 1.5 seconds.)
  transient
This one continues from where the last one left off: at 1.5 seconds. From now on, time will move forward.