public final double logPdf(double x){
  if (offset < 0)   return Math.log(0.0);
  return distribution.logPdf(x - offset);
}

public final double logPdf ( double x ) { if ( offset < 0 ) return Math . log ( 0.0 ) ; return distribution . logPdf ( x - offset ) ; }
log probability density function of the offset distribution
