**Two weeks ago i didn`t have problem with calculate and plot this pareto`s frontier. I got plot it, but if i try it now, i can´t . Why?.**

**Before**

f1 := (1+x1^2+4/3*(x2^2+1))/(x1+x2); f2 := (1+x1^2+3/4*(x2^2+1))/(x1+x2);

with(plots); with(Optimization); ind := 1; ans := Array(); for i from 1.73205080756887853 by 0.1e-4 while i < 2.87500000000000000 do roll := i; f1max := NLPSolve(f1, {f2 = i}, x1 = 0 .. 2, x2 = 0 .. 3, method = sqp, maximize = false); ans := proc (ind) options operator, arrow; [op([1], f1max), roll] end proc; ind := ind+1 end do; ans;

st := time[real]();

Array(%id = 18446746983952876598)

pointplot(convert(ans, list));

** After**

with(plots); with(Optimization); ind := 1; ans := Array(); for i from 1.73205080756887853 by 0.1e-4 while i < 2.87500000000000000 do roll := i; f1max := NLPSolve(f1, {f2 = i}, x1 = 0 .. 2, x2 = 0 .. 3, method = sqp, maximize = false); ans := proc (ind) options operator, arrow; [op([1], f1max), roll] end proc; ind := ind+1 end do; ans;

st := time[real]();

ans

pointplot(convert(ans, list));

**Error, (in plots:-pointplot) number of elements in list must be a multiple of 2 (????)**