# 34-lemniscata

Postscript("34-lemniscata.ps",1.6,1.2)
latox=c(-2,2); latoy=c(-1.5,1.5);
par(bg="#ccff99")
Grafica(latox,latoy,cornice=T)
x=seq(-2,2,by=0.01);
y=seq(-1.5,1.5,by=0.01)
f = function (x,y)
{u=x^2+y^2; u^2-x^2+y^2}
valori=outer(x,y,f)
Livelli(x,y,,valori=valori,scritte=0.5,
  livelli=setdiff(seq(-2,2,by=0.5),0))
Livelli(x,y,valori=valori,spessore=2,
  colore="red",scritte=0)
dev.off()