LLNAPI = function (){
  nmax <- 10000; Nmax <- 30;
  y <- matrix(as.integer(runif(Nmax*nmax)<0.5), nrow=Nmax, ncol=nmax);
  z <- y;
  for (j in 1:Nmax) {z[j,] <- cumsum(y[j,])/(1:nmax);}
  require(tcltk);
  k <- tclVar(5); 
  N <- tclVar(1);
  n <- tclVar(1000);
  distribution <- tclVar("bernoulli");

  base <- tktoplevel(); 
  tkwm.title(base,'Law(s) of Large Numbers');
  tt <- tkframe(base, borderwidth=2)
  sliderFrame <- tkframe(tt, borderwidth=2, relief='groove');



  NFrame <- tkframe(sliderFrame, borderwidth=2);
  NLabel <- tklabel(NFrame, text="Number of experiments", width=30);

  nFrame <- tkframe(sliderFrame, borderwidth=2);
  nLabel <- tklabel(nFrame, text="sample size", width=30);

  init <- function(){
    for (j in 1:Nmax){
      if (tclvalue(distribution)=="bernoulli"){
        y[j,]<<-as.integer(runif(nmax)<0.5);
      }
      else{
        y[j,]<<-rt(nmax, as.integer(tclvalue(k)));
      }
      z[j,] <<- cumsum(y[j,])/(1:nmax);
    }
  }

  replot <- function(N, n, ...){
    ym <- 0; yM <- 1;
    if (tclvalue(distribution)=="student") {yM <- max(abs(z[1:N, ])); ym<- -yM;}
    plot(1:n, array(0, n), type="n", ylim=c(ym, yM), xlab="1:n", ylab="cumulative mean")
    for (j in 1:N){
      lines(1:n, z[j, 1:n], type="l", col="blue", lwd=3, ...)
    }
  }
  controlPlot <- function(...){
    if (tclvalue(distribution)=="student"){
      tkconfigure(kSlider, state="normal", sliderrelief="raised");
    }
    else{
      tkconfigure(kSlider, state="disabled", sliderrelief="sunken");
    }
    replot(as.integer(tclvalue(N)), as.integer(tclvalue(n)));
  }

  otherPlot <- function(...){
    init(); controlPlot();
  }
  
  NSlider <- tkscale(NFrame, from=1, to=Nmax, length=600, showvalue=T, variable=N, resolution=1, orient='horizontal', command=controlPlot)
  tkpack(NFrame, NLabel, NSlider, side='left');
  
  nSlider <- tkscale(nFrame, from=50, to=nmax, length=600, showvalue=T, variable=n, resolution=50, orient='horizontal', command=controlPlot)
  tkpack(nFrame, nLabel, nSlider, side='left');

  tkpack(sliderFrame, NFrame, nFrame, side='top')
  
  rbFrame <- tkframe(tt, borderwidth=2,relief='groove');
  lbB <- tklabel(rbFrame, text='Bernoulli (1/2)'); 
  rbB <- tkradiobutton(rbFrame, command=otherPlot); 
  lbS <- tklabel(rbFrame, text='Student(k)');
  rbS <- tkradiobutton(rbFrame, command=otherPlot);
  tkconfigure(rbB, variable=distribution, value='bernoulli'); tkconfigure(rbS, variable=distribution, value='student');
  kFrame <- tkframe(rbFrame, borderwidth=2);
  kLabel <- tklabel(kFrame, text="Degrees of freedom", width=30);
  kSlider <- tkscale(kFrame, from=1, to=30, length=100, showvalue=T, variable=k, resolution=1, orient='horizontal', command=otherPlot)
  tkpack(kFrame, kLabel, kSlider, side='left');

  tkpack(rbFrame, lbB, rbB, lbS, rbS, side='left');
  tkpack(rbFrame, kFrame, side='right');
  
  tkpack(tt, rbFrame, sliderFrame, side='top');
}


LLNAPI();