expression函数在R图上增公式，数学符号

> x<-1:10

> y<-x^2

> plot(x,y)

> plot(x,y,ylab=expression(x^y))

> plot(1:10,ylab=expression(a[b]))

x<-1:10

> y<-sqrt(x)

> plot(x,y,ylab=expression(y==sqrt(x)))