82 lines
1.6 KiB
HolyC
Executable File
82 lines
1.6 KiB
HolyC
Executable File
//Classic 2nd order nonlinear ordinary differential equation
|
||
|
||
I64 mp_not_done_flags;
|
||
|
||
#define OX 10
|
||
#define OY GR_HEIGHT/2-FONT_HEIGHT
|
||
|
||
#define MICRO_STEP 0.000001
|
||
|
||
class State
|
||
{
|
||
F64 wabbits,hawks,
|
||
d_wabbits,d_hawks; //Technically, these are not part of the state.
|
||
};
|
||
|
||
U0 Steps(State *s)
|
||
{
|
||
I64 i;
|
||
for (i=0;i<10000;i++) {
|
||
s->d_wabbits=s->wabbits*(1.0-0.10*s->hawks);
|
||
s->d_hawks =-s->hawks *(1.0-0.01*s->wabbits);
|
||
s->hawks +=s->d_hawks *MICRO_STEP;
|
||
s->wabbits+=s->d_wabbits*MICRO_STEP;
|
||
}
|
||
}
|
||
|
||
U0 PlotTrajectory(CTask *parent)
|
||
{
|
||
I64 i;
|
||
CDC *dc=DCAlias(,parent);
|
||
State s;
|
||
|
||
MemSet(&s,0,sizeof(State));
|
||
s.wabbits=RandU16%100 +10;
|
||
s.hawks =RandU16%10 +1;
|
||
|
||
for (i=0;i<1000;i++) {
|
||
dc->color=LTGREEN;
|
||
GrPlot(dc,s.wabbits+OX,OY-s.d_wabbits);
|
||
dc->color=LTRED;
|
||
GrPlot(dc,s.hawks +OX,OY-s.d_hawks);
|
||
Steps(&s);
|
||
}
|
||
DCDel(dc);
|
||
LBtr(&mp_not_done_flags,Gs->num);
|
||
}
|
||
|
||
U0 PredatorPrey()
|
||
{
|
||
I64 i;
|
||
CDC *dc=DCAlias;
|
||
|
||
PopUpOk("This will plot multiple predator-prey\n"
|
||
"trajectories. It restarts many times\n"
|
||
"with different, random, initial populations.\n");
|
||
SettingsPush; //See $LK,"SettingsPush",A="MN:SettingsPush"$
|
||
try {
|
||
AutoComplete;
|
||
WinBorder;
|
||
WinMax;
|
||
DocClear;
|
||
Refresh;
|
||
|
||
dc->color=BLACK;
|
||
GrLine(dc,OX,0,OX,GR_HEIGHT-FONT_HEIGHT-1);
|
||
GrLine(dc,0,OY,GR_WIDTH-1,OY);
|
||
while (!ScanChar) {
|
||
mp_not_done_flags=1<<mp_cnt-1;
|
||
for (i=0;i<mp_cnt;i++)
|
||
JobQue(&PlotTrajectory,Fs,i);
|
||
do Yield;
|
||
while (mp_not_done_flags);
|
||
}
|
||
} catch
|
||
PutExcept;
|
||
SettingsPop;
|
||
DCFill(dc);
|
||
DCDel(dc);
|
||
}
|
||
|
||
PredatorPrey;
|