prologues := 3; beginfig(1);  pair orig; orig = (5cm,5cm); axisposlen = 3cm; axisneglen = 1cm; z1 = orig - (axisneglen,0);       % left end of x axis vectorang = 65; z2 = orig - 1cm * dir vectorang;  % start of vector line z3 = orig + 3cm * dir vectorang;  % end of vector line  % axes pair axisend[]; axisend1 = orig + (axisposlen,0); draw z1--axisend1; label.rt(btex $x$ etex, axisend1); axisend2 = orig + (0,axisposlen); draw (orig - (0,axisneglen))--axisend2; label.top(btex $y$ etex, axisend2); axisend3 = orig + axisposlen * dir 45; draw (orig - axisneglen * dir 45)--axisend3; label.rt(btex $z$ etex, axisend3); pickup pencircle scaled 4pt; drawdot(orig);  % dotted line for phi angle z4 = 0.8[orig,z3]; z5 = (x4, ypart orig + 0.5cm); linecap := butt; pickup defaultpen; draw z4--z5--orig dashed evenly;  % theta and phi labels and their curves angdist = 0.8cm; z6 = orig + angdist * up; draw z6{right}..(orig + angdist * dir vectorang); label.lft(btex $\theta$ etex, z6); z7 = orig + angdist * right; draw z7{up}..(orig + angdist * unitvector(z5 - orig)); label.bot(btex $\phi$ etex, z7);  % vector pickup pencircle scaled 1pt; linecap := rounded; drawarrow z2--z3; label.ulft(btex $(x,y,z)$ etex, orig); label.rt(btex $L(x,y,z,\theta,\phi)$ etex, z3);  endfig; end