25 setxunit 7.5 setborder 90 setangle_repere -.5 6 setxrange -4 8 setyrange /quadrillagegray 0.4 def 1 setquadrillagexstep 1 setquadrillageystep quadrillage 1 1 settkstep .5 .5 setsubtkstep 1 1 setmkstep ticks marks traceaxes unites