beginfig(1);
u=1cm;
sc=0.35u; xl=3u; yl=4u;
path p, pl;
p=unitsquare xscaled xl yscaled yl;
draw p shifted (2*sc,-0);
fill p shifted (sc,sc) withcolor white;
draw p shifted (sc,sc);
fill p shifted (0,2*sc) withcolor white;
draw p shifted (0,2*sc);
pl=(0.5u,0.5u)--(0.5u,yl-0.5u);
draw pl shifted (0,2sc) dashed evenly;
draw pl shifted (0.5u,2sc) dashed evenly;
draw pl shifted (0.5u*2,2sc) dashed evenly;
draw pl shifted (0.5u*4,2sc) dashed evenly;
picture ldz; ldz=thelabel(btex $\Delta\varphi$ etex, (0.4u,2.5u));
unfill bbox ldz; draw ldz;
picture lfa; lfa=thelabel(btex $f_1$ etex, (1u,2.5u));
unfill bbox lfa; draw lfa;
picture lfb; lfb=thelabel(btex $f_2$ etex, (1.5u,2.5u));
unfill bbox lfb; draw lfb;
picture lfn; lfn=thelabel(btex $f_n$ etex, (2.5u,2.5u));
unfill bbox lfn; draw lfn;
label.urt(btex $p_1$ etex, (xl,yl) shifted (0,2sc));
label.urt(btex $p_2$ etex, (xl,yl) shifted (sc,sc));
label.urt(btex $p_m$ etex, (xl,yl) shifted (2sc,0));
picture pic; pic=currentpicture;
pic:=pic shifted (6u,0);
draw pic;
label.lft(btex $\varphi_1:\quad$ etex, (0,2.25u));
label.lft(btex $\varphi_2:\quad$ etex, (6u,2.25u));
endfig;

end