//@code
objref vec, xvec, errvec
objref g
g = new Graph()
g.size(0,100, 0,250)
vec = new Vector()
xvec = new Vector()
errvec = new Vector()

vec.indgen(0,200,20)
xvec.indgen(0,100,10)
errvec.copy(xvec)
errvec.apply("sqrt")
vec.ploterr(g, xvec, errvec, 10)
vec.mark(g, xvec, "O", 5)