quniform.m

非常好的数字处理教程

function [x,y,D,H] = quniform(N,var,quanttype,disttype)
	V = sqrt(3*var);
	switch quanttype
		case 'uniform'
			% Even number of levels
			if rem(N,2) == 0
				del = 2*V/N;
				x = [0:N]*del-V;
				y	= [1:N].*del-V-del/2;
			else
				del = 2*V/N;
				x	= [0:N].*del-V;
				y = [0:N-1]*del-V+del/2;
			end
		case 'optimal'

			% Even number of levels
			if rem(N,2) == 0
				del = 2*V/N;
				x = [0:N]*del-V;
				y	= [1:N].*del-V-del/2;
			else
				del = 2*V/N;
				x	= [0:N].*del-V;
				y = [0:N-1]*del-V+del/2;
			end
	end
	
	% Distortion
	D = 0;
	switch disttype
		case 'squared error'
			for i=1:N
				D = D + (x(i+1)-y(i))^3 - (x(i)-y(i))^3;
			end
			D = D/(6*V);
		case 'absolute error'
			if rem(N,2) == 0
				for i=N/2+1:N	
					D = D + (y(i)-x(i))^2 + (x(i+1)-y(i))^2;
				end
			else
				for i=(N+1)/2+1:N
					D = D + (y(i)-x(i))^2 + (x(i+1)-y(i))^2;
				end
			end
			D = D/(2*V);
	end
	

	% Entropy
	H = 0;
	for i=1:N
		p = 1/(2*V)*(x(i+1)-x(i));
		H = H - p*log2(p);
	end