2011/5/23 Wolfgang Schuster
Please send a complete example!
Sure: \startMPdefinitions{solvers} \stopMPdefinitions \starttext Hello. \stoptext or this: \startMPdefinitions{solvers} def draw_problem (expr p, q, r, s, show_lables)= begingroup ; save x, y, a, b, c, d, e, f, g, h ; z11=z42=p ; z21=z12=q ; z31=z22=r ; z41=z32=s ; a=x12-x11 ; b=y12-y11 ; c=x22-x21 ; d=y22-y21 ; e=x32-x31 ; f=y32-y31 ; g=x42-x41 ; h=y42-y41 ; z11=(x11, y11) ; z12=(x12, y12) ; z13=(x12-b, y12+a) ; z14=(x11-b, y11+a) ; z21=(x21, y21) ; z22= (x22, y22); z23=(x22-s,y22+c) ; z24=(x21-d, y21+c) ; z31=(x31, y31) ; z32=(x32, y32) ; z33=(x32-f, y32+e) ; z34=(x31-f, y31+e); z41=(x41, y41) ; z42=(x42, y42) ; z43=(x42-h,y42+g) ; z44=(x41-h,y41+g) ; pickup pencircle scaled .5pt ; draw z11--z12--z13--z14--cycle ; draw z11--z13 ; draw z12--z14 ; draw z21--z22--z23--z24--cycle ; draw z21—z23 ; draw z22—z24 ; draw z31--z32--z33--z34--cycle ; draw z31—z33 ; draw z32—z34 ; draw z41--z42--z43--z44--cycle ; draw z41—z43 ; draw z42—z44 ; z1=0.5[z11,z13] ; z2=0.5[z21,z23] ; z3=0.5[z31,z33] ; z4=0.5[z41,z43] ; draw z1--z3 dashed evenly ; draw z2--z4 dashed evenly ; z0=whatever[z1,z3]=whatever[z2,z4] ; mark_rt_angle (z1,z0,z2); if show_labels>0: draw_problem_labels ; fi; endgroup ; enddef ; \stopMPdefinitions \starttext Hello. \stoptext Result is the same. Vedran