\ Lorenz Equation - Simulating Chaos

\ Equations:  dx/dt = a(y - x)  dy/dt = bx - xz - y  dz/dt = xy - cz


fl

\ save file in eeprom
fswrite lorenz.f

: (LORENZ) ;

decimal


\ Multiplier redefined to allow overfow.
: MULTX  Y() swap Y() Y0 */  TO swap Y()  ;

16 NODES

MODEL: LORENZ  4 7 RK2  5 4 INV  6 5 8 SUM  1 Kx 7 6 POT 
       8 13 RK2  2 Kx 9 4 POT  10 4 8 MULTX  11 4 14 MULTX  12 8 9 11 SUM  13 12 INV
       14 16 RK2  3 Kx 15 14 POT  16 10 15 SUM  ;    

sc
 \ All parameters are set t0 produce the "butterfly".  See Sept & Oct issues of 
 \ Elektor for a discussion of the CHAOS Machine. 

3000000 4  15000000 8  1000000 14 ASSIGN-IC     \  x - 4   y - 8  z - 14

 100000 TO 1 Kx    \ a - Prandtl Number 
-280000 TO 2 Kx    \ b - Raleigh Number  
-26667  TO 3 Kx    \ c - Proportion

5 TO DT   20 TO COMINT


OUTPUT-IS (display)


14 8 4 OUT-NODES

SIMULATE LORENZ

...


{  Requirements for plotting Lorenz equation solutions. Execute the following
    words after loading lorenz.f.

  OUTPUT-IS (xyplot)
  30 Y0 * TO Yx    \ Yx scales output data for plotting
  1 TO 1 N()  \ y-axis
  2 TO 2 N()  \ x-axi
\ set plot screen dimensions
  75 TO YSCALE   75 TO YLEVEL
  60 TO XSCALE   60 TO XLEVEL
  1000 PRUN  \ then press F4 to open xy-plot screen
\ press F7 to stop plot before run is copmleted if desired


}