y1=[3 0]';
A=[1.0 0.3;0.3 1.0];
y2=[-3 0]';
subplot(3,1,1)
C1=plot_normal(y1,A);
subplot(3,1,2)
C2=plot_normal(y2,A);
C=0.5*C1+0.5*C2;
range=5;
x1=-range:0.02:range;
x2=x1;
subplot(3,1,3)
mesh(x1,x2,C);