import geometry;
size(12cm,0);

currentcoordsys=cartesiansystem((0,0),i=(1,0.5),j=(-0.5,.75));
show(currentcoordsys, xpen=invisible);

point F=(2,-1.5);
dot("$F$",F,N,red);

// Enlarge the bounding box of the current picture.
draw(box((-0.5,-0.4),(4,1.5)),invisible);

parabola p=parabola(F,0.2,90);

// Define the bounding box to draw the parabola.
// Try finalbounds(); to determine the final bounding box.
p.bmin=(-0.5,-0.4);
p.bmax=(3.7,0.75);

draw(p,dashed); /* Defered drawing to adjust the path to the final
                   bounding box.*/

draw((path)p); /* The path of 'p' is restricted to the box whose
                  the corners are p.bmin, p.bmax.*/

/* View the definition of point relpoint(explicit parabola,real) */
dot("relpoint(p, 0)",relpoint(p,0),SE);

/* View the definition of point point(parabola,abscissa) */
dot("relpoint(p, 0.25)",point(p,Relative(0.25)),NE);
// point(p,Relative(0.25)) can be replaced by relpoint(p,0.25) OR point(p,relabscissa(0.25))

dot("relpoint(p, -0.5)",relpoint(p,-0.5),W);
dot("relpoint(p, -1)",relpoint(p,-1),W);
dot("relpoint(p, 1)",relpoint(p,1),E);

    
import geometry;
size(10cm);

point F=(1,-1.5);
dot("$F$",F,N,red);

parabola p=parabola(F,0.2,110);

draw(p);

/* View the definition of point curpoint(explicit parabola,real) */
dot("curpoint(p, 0)",curpoint(p,0),SE);

/* View the definition of point point(parabola,abscissa) */
dot("curpoint(p, 0.5)",point(p,curabscissa(0.5)),NE);
// point(p,curabscissa(0.5)) can be replaced by curpoint(p,0.5)

dot("curpoint(p, -0.5)",curpoint(p,-0.5),W);
dot("curpoint(p, -2)",curpoint(p,-2),W);
dot("curpoint(p, 2)",curpoint(p,2),E);

    
import geometry;
size(10cm);

point F=(1,0.5);
dot("$F$",F,E,red);

parabola p=parabola(F,0.2,110);

draw(p);

coordsys R=currentcoordsys;
show(R);

coordsys Rp=canonicalcartesiansystem(p);
show(Label("$O'$",align=NW+W,blue), Label("$\vec{u}$",blue), Label("$\vec{v}$",blue), Rp, ipen=blue);

/* View the definition of point angpoint(explicit parabola,real) */
dot("angpoint(p, 180)",angpoint(p,180),SE+E);

/* View the definition of point point(parabola,abscissa) */
point P=point(p,angabscissa(55));
// point(p,angbscissa(0.5)) can be replaced by angpoint(p,0.5)
dot("angpoint(p, 55)",P,NE);

segment s=segment(F,P);
draw(s);
line l=line(F,F+Rp.i);
markangle("$"+(string)degrees(l,s)+"^\circ$",l,(line)s,Arrow);

dot("angpoint(p, -45)",angpoint(p,-45),W);
dot("angpoint(p, -55)",angpoint(p,-55),W);

    
import geometry;
size(12cm);

// currentcoordsys=cartesiansystem((0,0),i=(1,0.5),j=(-0.5,.75));
show(currentcoordsys, xpen=invisible);

point F=(2,-1.5);
dot("$F$",F,N,red);

// Enlarge the bounding box of the current picture.
draw(box((-0.5,-0.4),(4,1.5)),invisible);

parabola p=parabola(F,0.2,90);

draw(p,bp+dashed); /* Defered drawing to adjust the path to the final
                   bounding box.*/

// Define the bounding box to draw the parabola.
// Try finalbounds(); to determine the final bounding box.
p.bmin=(-0.5,-0.4);
p.bmax=(3.7,0.75);
draw((path)p, linewidth(bp)); /* The path of 'p' is restricted to the box whose
                  the corners are p.bmin, p.bmax.*/

/* View the definition of point point(explicit parabola,explicit real) */
dot("point(p, 0)", point(p,0),2E,3mm+blue);

dot("point(p, 15)", point(p,15),2W,3mm+blue);

/* View the definition of abscissa nodabscissa(real) */
dot("point(p, 40)", point(p,nodabscissa(40)), 2W,3mm+blue);
// point(p,nodabscissa(40)) can be replaced by point(p,40)

/* View the definition of real[] bangles(picture,parabola) */
real[] bg=bangles(p);

/* View the definition of int parabolanodesnumber(parabola,real,real) */
dot("point(p, parabolanodesnumber(p,bg[0],bg[1])/2)",
    point(p, parabolanodesnumber(p,bg[0],bg[1])/2), S, 3mm+blue);

dot((path)p, yellow);