import graph_pi;
usepackage("mathrsfs");
size(10cm,0);

graphicrules(xunit=1cm, yunit=1cm, 
	     xmin=-4, xmax=4, 
	     ymin=-4, ymax=4, 
	     crop=Crop
	     );
grid(xStep=1, xstep=.5,
     yStep=1, ystep=.5,
     pTick=.8red, 
     ptick=dotted+.7bp+.4white,
     above=false
     );
cartesianaxis(
       p=currentpen,
       xticks=Ticks(Label(Fill(white)),
                    Step=2,
                    NoZero,
                    pTick=.5mm+blue,ptick=grey),
       yticks=Ticks(Label(Fill(white),
                          align=NE),
                    Step=2,
                    NoZero,
                    pTick=.5mm+blue,ptick=grey),
       viewxaxis=true,
       viewyaxis=true,
       above=true,
       arrow=Arrow
       );
labeloij(p=1.4bp+.5*red,
         arrow=Arrow(SimpleHead,8bp),
         dot
         );
// Définition de la fonction
real f(real x) {return 1/x;}
// Tracé de la courbe
path Cf1=graph(f,-5,-0.001,n=200);
path Cf2=graph(f,0.001,5,n=200);
draw(Cf1,dashed+1bp);
draw(Cf2,linewidth(1bp));
xlimits(-4.5,4.5,Crop);
ylimits(-4.5,4.5,Crop);         
label("$\mathscr{C}_f$",(.4,f(.4)),NE);