logPdf Output the log pdf of the random variable evaluated at the points specified
 
  logpdf = RV.logpdf(X) returns the logarithm of value of the
  pdf of the prtRv object evaluated at X. X must be an N x
  nDims matrix, where N is the number of locations to evaluate
  the pdf, and nDims is the same as the number of dimensions,
  nDimensions, of the prtRv object RV.