timefunc.txt

pic 模拟程序！面向对象

Boundaries can exhibit time dependent behavior.
Which boundary exhibits what behavior depends on the
boundary, but it is usually pretty clear.

Equipotentials have a time dependent voltage,
beam emitters have time dependent currents.


The time dependency is a function of the form

Envelope(t) * Sinusoid(t)

when time_function_flag = 0

See "String Time Functions" below for time_function_flag = 1

The envelope function looks like this:

  magnitude
   |
   |
a1 |                **********
   |               *          *
   |              *            *
   |             *              *
   |            *                *
   |           *                  *
a0 | **********                    ********
   |
   |----------+-----+--------+-----+------------    t
   0
    --------->|      	              tdelay
              |<--->|	              trise
                    |<------>|        tpulse
                             |<--->|  tfall

So the parameters controlling the envelope function are:
a0 a1 tdelay trise tpulse and tfall.

The sinusoid is parameterized by:

Sinusoid(t) = A*sin(2*pi*frequency*t + phase) + C

The parameters of the sinusoid are:

phase
frequency
A
C


You can modify the behavior of the timefunction
yourself if these parameters aren't sufficient for your
purposes.

The file is physics/timefunc.h



String Time Functions

A facility has been added which will allow you to put in
more flexible functions of time which you may need, which
doesn't fit in the Sinusoid * Envelope template provided
above.

To do this, you add:
time_function_flag = 1
F = <your function here>

to the boundary you want to control.

Most of the usual mathematical functions are understood:
as of now the variables you can use are:

"t":  the current simulation time

F = sin(t)

F = sin(t) * cos(t)

F = sin(t)^2

F = 10e9* (t%1e-9)
 (an explanation of this last:  the % operator means "divide and take
  the remainder" so that (t%1e-9) takes the values of 0 to 1e-9 in
  a periodic fashion of period 1e-9.  Using this operator you can make
  an arbitrary function periodic:)

F = exp( t%1e-10)

In addition, these special functions are added, to make pulse
functions:

pulse(t,tdelay,trise,tpulse,tfall)   :  like the envelope function above
step(x)	:  returns 0 if x < 0 and returns 1 otherwise
ramp(x) :  returns 0 if x < 0 and returns x otherwise

See evaluator.txt for additional information.