question: public static double logPdf ( double x , double m , double shape ) { double a = Math . sqrt ( shape / ( 2.0 * Math . PI * x * x * x ) ) ; double b = ( ( - shape ) * ( x - m ) * ( x - m ) ) / ( 2.0 * m * m * x ) ; return Math . log ( a ) + b ; }
target:  the natural log of the probability density function of the distribution