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.')

Version History

Introduced in R2008a