TITLE Spring2 - Spring model with multiple SOLVEs
:  Simulation Resources, Inc.
:  Same model as spring.mod, except in this file there
:  are three state variables (x,y,z) solved separately
:  in BREAKPOINT with three separate SOLVE statements.
:  There is a slight variation in the solution, compared
:  with the model with a single variable, because of
:  the automatic time step adjustment in the adrunge
:  integration algorithm. Note: this method works only
:  when the independent variable for the calculation is
:  the same as the mathematical independent variable.
:  3/10/1999

PARAMETER
{
  m = 10        (kg)            k = 80          (N/m)
  c = 5         (N-sec/m)
}

STATE
{
  x FROM -15 TO 15 START 10     (m)
  y FROM -15 TO 15 START 10     (m)
  z FROM -15 TO 15 START 10     (m)


}

INDEPENDENT
{
  time FROM 0 TO 8 WITH 80      (sec)
}

PLOT x,y VS time

DERIVATIVE motion
{
  x'' = (- 1/m)*(k * x + c * x')
}
DERIVATIVE motiony
{
  y'' = (- 5/m)*(k * y + c * y')
}
DERIVATIVE motionz
{
  z'' = (- 5/m)*(k * z + c * z')
}


BREAKPOINT
{
        : Save the time variables.
        : Note that "time" is the independent
        : variable for the model (change as
        : needed).
  LOCAL save_time, save_indep
  save_time = time
VERBATIM
  _lsave_indep = _sav_indep;
ENDVERBATIM
  SOLVE motion

        : Reset the time variables for the
        : next SOLVE statement.
  time = save_time
VERBATIM
  _sav_indep = _lsave_indep;
ENDVERBATIM
  SOLVE motiony

        : Repeat as needed for other independent
        : SOLVE statements.
  time = save_time
VERBATIM
  _sav_indep = _lsave_indep;
ENDVERBATIM
  SOLVE motionz

}