param N := 3;

param A {1..4};
param D {1..4};
param G{1..4,1..3};
param B{1..3,1..3};

var x{1..N} := 0.1;
var F{i in 1..4} = A[i] + sum {j in 1..3} G[i,j]*x[j] + 0.5*(sum {j in 1..3} (x[j]*sum {k in 1..3} B[j,k]*x[k]))*D[i];

minimize f:
sum {i in 1..4} F[i]^2;

data;
param A:=
1	0.14272
2	-0.184918
3	-0.521869
4	-0.685306;

param D:=
1	1.75168
2	-1.35195
3	-0.479048
4	-0.3648;

param G:
	1			2			3:=
1	-0.564255	0.392417	-0.404979	
2	0.927589	-0.0735084	0.535493
3	0.658799	-0.636666	-0.681091
4	-0.869487	0.586387	0.289826;

param B:
	1			2			3:=
1	2.95137		4.87407		-2.0506
2	4.87407		9.39321		-3.93181
3	-2.0506		-3.93189	2.64745;

solve;

display x;