pdeg = 4
pbot = polyfit([1 2 3 4], [0 0 0 0], pdeg);
pright = polyfit([1 2 3 4], [20 40 60 80], pdeg);
ptop = polyfit([1 2 3 4], [50 20 10 0], pdeg);
pleft = polyfit([1 2 3 4], [20 40 60 80], pdeg);

ix = 0.5:0.5:4.5;
itp_bot = polyval(pbot, ix);
itp_right = polyval(pright, ix);
itp_top = polyval(ptop, ix);
itp_left = polyval(pleft, ix);

s = lapsolve1(itp_bot, itp_right, itp_top, itp_left);

surf(s)

