public static double logpdf(double x, double mu, double sigma) {
    x = (x - mu) / sigma;
    return MathUtil.LOG_ONE_BY_SQRTTWOPI - FastMath.log(sigma) - .5 * x * x;
  }
public static double logpdf ( double x , double mu , double sigma ) { x = ( x - mu ) / sigma ; return MathUtil . LOG_ONE_BY_SQRTTWOPI - FastMath . log ( sigma ) - .5 * x * x ; }
Log probability density function of the normal distribution.
<p>
\[\log\frac{1}{\sqrt{2\pi}} - \log\sigma - \tfrac{(x-\mu)^2}{2\sigma^2}\]

@param x The value.
@param mu The mean.
@param sigma The standard deviation.
@return PDF of the given normal distribution at x.