Eric Sven Ristad and Peter N. Yianilos.
The current LIBPA release is a source code distribution. It consists of modules for portable memory management, one dimensional arrays of arbitrary types, compact symbol tables, hash tables for arbitrary types, a trie module for length-delimited strings over arbitrary alphabets, single precision floating point numbers with extended exponents, and logarithmic representations of probability values using either fixed or floating point numbers.
We have used LIBPA to implement a wide range of statistical models for both continuous and discrete domains. The time and space efficiency of LIBPA has allowed us to build larger statistical models than previously possible, and to investigate more computationally-intensive techniques. We have found LIBPA to be indispensable in our own research, and hope that you will find it useful in yours. If you find LIBPA useful, please let us know!