In my project, I generate random samples from N1, N2 ,N3 and i plot them and x is a 2 dimensional guassian distribution N(meani,sigmai). but I want also to plot the bayes decision regions for equal and different initial prob. can anyboby help me plz?

clear all

close all

%N1

mean1=[0 0];

sigma1=[1 0; 0 1];

%N2

mean2=[1 1];

sigma2=[1 0;0 4];

%N3

mean3=[2 2];

sigma3=[1 -1;-1 4];

x1 = -4:.2:4;

x2 = -4:.2:4;

[X1,X2] = meshgrid(x1,x2);

y1=mvnpdf([X1(:) X2(:)],mean1,sigma1);

y1 = reshape(y1,length(x2),length(x1));

surf(x1,x2,y1);

caxis([min(y1(:))-.5*range(y1(:)),max(y1(:))]);

axis([-4 4 -4 4 0 .2])

xlabel('x1'); ylabel('x2'); zlabel('Probability Density');

figure(1)

hold on

y2=mvnpdf([X1(:) X2(:)],mean2,sigma2);

y2 = reshape(y2,length(x2),length(x1));

surf(x1,x2,y2);

caxis([min(y2(:))-.5*range(y2(:)),max(y2(:))]);

axis([-4 4 -4 4 0 .2])

xlabel('x1'); ylabel('x2'); zlabel('Probability Density');

hold on

y3=mvnpdf([X1(:) X2(:)],mean3,sigma3);

y3 = reshape(y3,length(x2),length(x1));

surf(x1,x2,y3);

caxis([min(y3(:))-.5*range(y3(:)),max(y3(:))]);

axis([-4 4 -4 4 0 .2])

xlabel('x1'); ylabel('x2'); zlabel('Probability Density');

s1=mvnrnd(mean1,sigma1,30);

i=zeros(1,30);

figure(2)

plot(s1,i,'v')

hold on

s2=mvnrnd(mean2,sigma2,30);

i=zeros(1,30);

plot(s2,i,'r*')

hold on

s3=mvnrnd(mean3,sigma3,30);

i=zeros(1,30);

plot(s3,i,'+')

figure(3)

c1=contour(x1,x2,y1);

hold on

c2=contour(x1,x2,y2);

hold on

c3=contour(x1,x2,y3);