Statistics: lognpdf

### Function Reference: `lognpdf`

statistics: y = lognpdf (x)
statistics: y = lognpdf (x, mu)
statistics: y = lognpdf (x, mu, sigma)

Lognormal probability density function (PDF).

For each element of x, compute the probability density function (PDF) of the lognormal distribution with mean parameter mu and standard deviation parameter sigma, each corresponding to the associated normal distribution. The size of y is the common size of p, mu, and sigma. A scalar input functions as a constant matrix of the same size as the other inputs.

If a random variable follows this distribution, its logarithm is normally distributed with mean mu and standard deviation sigma.

Default parameter values are `mu = 0` and `sigma = 1`. Both parameters must be reals and `sigma > 0`. For `sigma <= 0`, `NaN` is returned.

Further information about the log-normal distribution can be found at https://en.wikipedia.org/wiki/Log-normal_distribution

See also: logncdf, logninv, lognrnd, lognfit, lognlike, lognstat

Source Code: lognpdf

### Example: 1

     ## Plot various PDFs from the log-normal distribution
     x = 0:0.01:5;
     y1 = lognpdf (x, 0, 1);
     y2 = lognpdf (x, 0, 0.5);
     y3 = lognpdf (x, 0, 0.25);
     plot (x, y1, "-b", x, y2, "-g", x, y3, "-r")
     grid on
     ylim ([0, 2])
     legend ({"μ = 0, σ = 1", "μ = 0, σ = 0.5", "μ = 0, σ = 0.25"}, ...
              "location", "northeast")
     title ("Log-normal PDF")
     xlabel ("values in x")
     ylabel ("density")