Gr.postscript('29505-logspir.ps',4,3)
latox=c(-20,20); latoy=c(-15,15);
par(bg="yellow")
Gr(latox,latoy,cornice=T)
t=seq(-10,10,by=0.01)
lines(exp(t/4)*cos(t),exp(t/4)*sin(t))
dev.off()