Depending on your computer (80386, 80486, or Pentium) you may need to
adjust the speed of the animation. You can do this while the
simulation is running by using the hot keys at the bottom of the screen or
by using the [Preferences]|[Speed]
menu.
Although it was easy for us to decrease animation speed by adding a Pascal
PAUSE(t)
command, increasing the animation speed requires some type of
trade off. We have chosen to increase the animation speed by skipping screen redraws. This can produce a ``jerky" wave, but because drawing frequency (as opposed to the time
step, 
), is varied, the underlying numerical algorithm is unchanged.
Thus, the accuracy of the calculation is not affected by varying animation speed.
Caution: Because analysis graphs record data only when the screen is
redrawn, increasing the speed by performing multiple time step calculations
between screen redraws can result in distortion of analysis plots if the
sampling frequency is small compared to the frequency of the simulated
wave.
Adjusting the number of grid points under menu item [Parameters]|[Space Parameters]
allows the user to trade accuracy for speed and is a good way to control animation. Setting NumPts
should be
done at the beginning of a session since it will clear the
analysis graphs.
Adjusting the time step is not a good way to control the speed.
The classical wave, Klein-Gordon, sine-Gordon,
phi-four, and double sine-Gordon calculations use an algorithm which
automatically sets 
; thus, the time step, 
,
is determined by the number of grid points, which in turn specifies 
.
The Schrödinger and diffusion equations allow the user to set 
independently of 
by choosing the [Parameters]|[Time
Parameters]
option. Our algorithms are, however, unstable if 
is too
large. Whenever NumPts
is changed, the program does
the right thing. It automatically sets 
to 
the maximum stable value. Since 
is proportional to
for both the Schrödinger and the diffusion equations,
adjusting NumPts
will have a dramatic effect on the calculation speed.
Data analysis can significantly affect the speed of program execution.
Some graphs, such as the Fourier Analysis of amplitude, 
, require a great deal of calculation. Other graphs, such as
the contour plot, spend most of their time just sitting in memory and collecting data
and only once in a while perform the extensive calculations necessary for rendering. Expanding
the wave graph to full screen will disable many analysis calculations and allow faster
simulation. Time-consuming drawing will be eliminated
but data will still be collected and stored by the analysis graphs. This data
will be displayed when the wave graph is contracted.
Since control of the mouse is very CPU-intensive, disabling the mouse when the simulation is running will produce a noticeable speed enhancement. This can be done in the [Pref]|[Speed] menu.
Hint: Save the setup that provides the best compromise between smooth animation and accuracy for the Schrödinger and diffusion equations. Load these files as an alternate way to select the equation type.