plotting a piecewise function-help

I want to plot Vl versus vs

function Vl= piecewisefunnn(vs); vs1 = vs>0.6; Vl(vs1)=(vs(vs1)-0.6); vs2 =(vs<0.6 & vs==0.6); Vl(vs2) = 0; vs= -20:20; plot(vs,Vl(vs)) end

thanx for your help