\begin{verbatim}
# Change N where N is the desired number of runs
BEGIN {
  N=99;
  # how many times do we step through the model
  TIMESTEPS=20;
  # how fine should the numeric appr be
  UNITSTEP=200;
  SMALL=.000001;
}
m4_include(includes/base_awk.m4)

# Model:
#    dx/dt = a1*x * ((k1-x - alpha*y)/k1)
#    dy/dt = a2*y * ((k2-y - beta*x)/k2)

# model parameters
Choice(a1SpyVal,=,n){
  return linear(a1SpyVal_min,a1SpyVal_max,n); }
Choice(k1SpyVal,=,n) {
  return linear(k1SpyVal_min, k1SpyVal_max,n); }
Choice(k2SpyVal,=,n) {
  return linear(k2SpyVal_min, k2SpyVal_max,n); }
Choice(alphaSpyVal,=,n){
  return linear(alphaSpyVal_min,alphaSpyVal_max,n); }
Choice(betaSpyVal,=,n) {
  return linear(betaSpyVal_min,betaSpyVal_max,n); }

function rho(  tmp) {
  tmp = a1SpyVal();
  #split 0-1 in half and then rescale
  if(tmp>.5)
    return (tmp+.5)*10;
  else
    return tmp*2;
}
function a12(   tmp){
  tmp = alphaSpyVal();
  #split 0-1 in half and then rescale to 0-1 and 1-15
  if(tmp>.5)
    return (tmp+.5)*10;
  else
    return tmp*2;
}
function a21(   tmp) {
  tmp = betaSpyVal();
  #split 0-1 in half and then rescale to 0-1 and 1-15
  if(tmp>.5)
    return (tmp+.5)*10;
  else
    return tmp*2;
}
function X0() {
  return (k1SpyVal()+.02)*2;
}
function Y0() {
  return (k2SpyVal()+.02)*2;
} 
function dx(x,y,   tmp) {
  tmp = x*(1-x-a12()*y);
  return tmp;
}
function dy(x,y,    tmp) {
  tmp = rho()*y*(1-y-a21()*x);
  return tmp;
}

# do time stepping in main function
function main(warmup,   n,delx,dely,xt,yt) {
  a1SpyVal(n);
  k1SpyVal(n);k2SpyVal(n);
  alphaSpyVal(n);betaSpyVal(n);

  xt=X0();yt=Y0();
  sumworth=0.0;
  REDO=0
  if (!warmup) {print "# new experiment" >> "points.dat";
    print count++ " " a12() " " a21() >> "parameters.dat";}
  do {
    REDO++;
    if (!warmup) {print xt " " yt " " sumworth >> "points.dat";
    }
    delx = dx(xt,yt)/UNITSTEP;
    dely = dy(xt,yt)/UNITSTEP;
    xt += delx;xt=(xt<SMALL?0:xt);
    yt += dely;yt=(yt<SMALL?0:yt);
    sumworth = (abs(delx)<SMALL?0:1) + (abs(dely)<SMALL?0:1);
  } while (sumworth != 0 || REDO<10)
  return ((xt>.01?1:0)+(yt>.01?1:0));#sumworth;
}

function abs(x){ return (x<0?-x:x);}
\end{verbatim}