Any updates on this? Amuthan
On Tuesday, January 14, 2014 3:31:16 PM UTC-8, Brian Cohen wrote: > > Most code examples for Julia are aimed at users of existing statistical > and numerical software without demonstrating how functional programming can > be substantially more useful for their field. In many ways, Julia is a Lisp > without S-Expressions, so I didn't think it would be unwise to port code > examples from Structure and Interpretation of Classical Mechanics > <http://en.wikipedia.org/wiki/Structure_and_Interpretation_of_Classical_Mechanics> > > from Scheme to Julia. This book shows how functional programming can be > directly applied to the formalism of Lagrangian and Hamiltonian Mechanics, > but Scheme & SCMUtils > <http://groups.csail.mit.edu/mac/users/gjs/6946/refman.txt> may be too > obscure and syntactically different from what people are used to for most > people in the physical sciences. > > Book review: http://www.ids.ias.edu/~piet/publ/other/sicm.html > > I was impatient, and decided to just start porting code, so the first > example was easy enough: > > (define ((L-free-particle mass) local) > (let ((v (velocity local))) > (* 1/2 mass (dot-product v v)))) > > would become something like lFreeParticle(mass) = tuple -> begin v = > velocity(tuple); mass * dot(v,v) / 2 end. So far so good. > > But it's not long that I encounter usage of SCMUTILS > > (define q > (up (literal-function ’x) > (literal-function ’y) > (literal-function ’z))) > > So I turn to the Appendix which talks about Symbolic values in Scheme, and > confirming it in the SCMUTILS documentation, it appears that symbols have > the same type as real numbers, which seems very different than symbolic > expressions as described in the Julia documentation. Here, up constructs > a tuple, and literal-function is a constructor for symbolic manipulation. > At this point, I'm not sure how to proceed, but am still looking into the > matter. I see that the only packages that mention symbolic manipulation are > a SymPy interface and a Calculus package. >
