errpdf
Probability density function of quantization error
Syntax
[f,x] = errpdf(q)
f = errpdf(q,x)
Description
[f,x] = errpdf(q) returns the probability
density function f evaluated at the values in x.
The vector x contains the uniformly distributed
random quantization errors that arise from quantizing a signal by quantizer object q.
f = errpdf(q,x) returns the probability
density function f evaluated at the values in vector x.
Note
The results are not exact when the signal precision is close
to the precision of the quantizer.
Examples
Compute the PDF of the quantization error
q = quantizer('nearest',[4 3]); [f,x] = errpdf(q); subplot(211) plot(x,f) title('Computed PDF of the quantization error.')
The output plot shows the probability density function of the quantization error. Compare this result to a plot of the sample probability density function from a Monte Carlo experiment:
r = realmax(q);
u = 2*r*rand(10000,1)-r; % Original signal
y = quantize(q,u); % Quantized signal
e = y - u; % Error
subplot(212)
hist(e,20)
gca.xlim = [min(x) max(x)];
title('Estimate of the PDF of the quantization error.')
Introduced in R2008a