import geometry;
size(6cm,0);

// currentcoordsys=cartesiansystem((1,2),i=(1,0.5),j=(-0.5,.75));
// show(currentcoordsys, xpen=invisible);

point A=(-1,1);
dot("$A$",A,S);

arc a=arc(ellipse(A,2,1,45), 45, 270, fromCenter);
draw(a,linewidth(3mm),ArcArrow(5mm));

/* View the definition of arc arc(explicit arc,abscissa,abscissa) */
draw(arc(a,angabscissa(135),angabscissa(225)),1mm+red,ArcArrow(3mm),TrueMargin(0,0.5mm));