#######################################
# GR Grafica.

# Impostazione grafica.
Gr = function (x,y,cornice=F,
  rxy=1,assi=F,marg=0)
{par(mai=rep(marg,4), omi=c(0,0,0,0),
  lwd=0.5);
plot(x,y,type="n",xlab="",ylab="",
  asp=rxy,axes=assi,frame.plot=cornice)}

Gr.livelli = function (x,y,f,
  valori=NULL,livelli=0,
  scritte=1,colore=1,spessore=0.4)
{if (identical(valori,NULL))
  valori=outer(x,y,f);
contour(x,y,valori,levels=livelli,
  col=colore,lwd=spessore,
  labcex=0.6*scritte,
  drawlabels=(scritte>0),add=T)}

Gr.postscript = function (file,larg,alt)
{postscript(file,width=larg/2.54,
  height=alt/2.54, horizontal=FALSE,
  onefile=FALSE, paper="special")}
#######################################
# Octobrinidae.

Oct = function (x)
{2*sin(4*x)/(1+x*x)}