added solution to ex01

exercises/ex01/solutions/genrosm.mod

+reset;
+
+param n:=4;
+var x{1..n} := 2, >= -2, <=2;
+#var x{1..n} >= -2, <=2;
+display x;
+
+let x[1] := -1; #-1.0;
+let x[2] :=  1; # 0.5;
+let x[3] :=  1; # 0.4;
+let x[4] :=  1; # 0.3;
+display x;
+
+subject to
+cons1: -400*(x[1]*x[2]-x[1]^3)-2+2*x[1] = 0;
+cons{i in 2..n-1}: 200*(x[i]-x[i-1]^2)-400*(x[i+1]*x[i]-x[i]^3)-2+2*x[i] = 0;
+consn: 200*(x[n]-x[n-1]^2) = 0;
+
+#option solver conopt;
+#option solver knitro;
+#option solver loqo;
+#option solver minos;
+#option solver snopt;
+option solver ipopt;
+#option solver baron;
+#option solver couenne;
+
+solve;
+
+display x;

exercises/ex01/solutions/sol01.txt

+|------------------|
+| Solution of ex01 |
+|------------------|
+
+---
+1.2
+---
+
+Starting on the y-axis (e.g. at (0,10)), the local solvers
+- conopt
+- knitro
+- loqo
+- minos
+- snopt
+- ipopt
+can not find the global solution, and they end up with very large negative values of x.
+On the other hand, the global solvers
+- baron
+- couenne
+can find the global solution (3.0,0.5).
+
+---
+1.3
+---
+
+See beale_grad.mod
+
+---
+1.5
+---
+
+See genrosm.mod
+
+Stationary points:
+(1,1,1,1)                    -> global minimum
+(-0.776,0.613,0.382,0.146)   -> local minumum
+(-0.656,0.443,0.204,0.042)   -> saddle point
+