Importing Pre-packaged Software into Lisp: Experience with Arbitrary-Precision Floating-Point Numbers

We advocate the use of a Common Lisp as a central organizing environment for building scientific computing systems, based on its debugging features, interactivity, memory model, existing code-base for computer algebra and user interfaces, and its ability to dynamically load modules written in other languages. In this paper we primarily address one example of mixing pre-existing (non Lisp) code into this system: an elaborate FORTRAN system written by David Bailey for arbitrary-precision floatingpoint numeric calculation. We discuss the advantages and disadvantages of wholesale importing such a system into Lisp. The major advantage is being able to use state-of-the art packaged software interactively while overcoming the disadvantages caused by FORTRAN’s traditional batch orientation and weak storage model. In this paper we emphasize in particular how effective use of imported systems may require one to address the contrast between the functional (Lisp-like) versus state-transitionbased (Fortran-like) approaches to dealing with compound objects. While our main example is high-precision floats, we mention other highly-useful packages including those for simulation, PDE solutions, signal processing, statistical computation, linear algebra (LAPACK) that have also been used with Lisp. We provide pointers to additional applications of this