help me in understanding the code

ANJAY PALIWAL

2012 4 15

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clear,
clc;
pdf='exp(-(x-m).^2/2/sigma^2)/sqrt(2*pi)/sigma'; %Gaussian pdf of x
xf=inline(['x.*' pdf],'x','m','sigma');
f=inline(pdf,'x','m','sigma');
m=0; sigma=1; % Mean and variance of the random variable x
b0=-3; bN=3; % Given least/greatest value of the random variable x
for N=5:6 % Number of quantization intervals
 delta=(bN-b0)/N; 
 b=b0+[0:N]*delta;
 msqe=0; % Mean-Square Quantization Error
 for i=1:N % Centroid of each interval
 tmp1=quad(xf,b(i),b(i+1),0.01,[],m,sigma);
 tmp2=quad(f,b(i),b(i+1),0.01,[],m,sigma);
 tmp=tmp1/tmp2;  c(i)=tmp;  % Eq.(4.1.1)
 x2f=inline(['(x-tmp).^2.*' pdf],'x','m','sigma','tmp');
 msqe=msqe+quad(x2f,b(i),b(i+1),0.01,[],m,sigma,tmp); % Eq.(4.1.2)
   end
    % Resulting boundary vector and centroid vector
   x=b0+(bN-b0)/1000*[0:1000];
   y(find(x<b(1)))=c(1); % Left-most interval
   for i=1:N,  y(find(b(i)<=x&x<b(i+1)))=c(i);  end
   y(find(x>=b(N+1)))=c(N); % Right-most interval
   subplot(2,2,N-4), 
   plot(x,y),
   hold on,
   grid on % Quantization graph
   m=0; sigma=1; fx=feval(f,x,m,sigma);
   plot(x,fx,'r:') ;
    % Resulting MSQE
end

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Walter Roberson 2012-4-15

Please be more specific in your question. For example are you stuck at the "clc" call, or are you stuck on logical indexing, or are you stuck in understanding what the [] argument to quad() means?