y=seq(-6,6,len=101)
svg("logit-probit.svg")
par(cex=1.5,mai=c(0.8,0.8,0.1,0.1))
plot.new(); plot.window(c(0,1),range(y))
box(lwd=0.3); axis(1, at=seq(0,1,len=5)); axis(2)
abline(h=0,v=0.5,lty=3)
lines(plogis(y),y,lwd=3,col="royalblue")
lines(pnorm(y*sqrt(pi/8)),y,lty=3,lwd=3,col="tomato")
legend("bottomright", c("logit", "probit (scaled)"), col = c("royalblue","tomato"), lty=c(1,3),lwd=3)
dev.off()