Date: Mon, 22 Mar 1999 12:33:11 -0600 (EST)
From: James Hague <jhague@dadgum.com>
To: caml-list@inria.fr
Subject: Numeric programming efficiency question
First of all, let me say that I've been having a great time learning
Objective CAML!
I implemented some simple functions that operate on three dimensional
vectors. After reading the "Numeric Programming in CAML" document, it
seems that, unfortunately, the code resulting from using a more classic
syntax is less efficient than using structures. That is, this:
let vadd (x0,y0,z0) (x1,y1,z1) = (x0 +. x1, y0 +. y1, z0 +. z1);;
generates poorer code than:
type vector = {x: float; y: float; z: float};;
let vadd a b = {x = a.x +. b.x; y = a.y +. b.y; z = a.z +. b.z};;
When using this function, one implementation has a more concise calling
syntax:
vadd (1.0,2.0,3.0) (10.0,20.0,30.0);;
vadd {x=1.0;y=2.0;z=3.0} {x=10.0;y.0;z=30.0};;
A utility routine makes the second option a little nicer:
let vec (a,b,c) = {x=a; y=b; z=c};;
This lets one write:
vadd vec(1.0,2.0,3.0) vec(10.0,20.0,30.0);;
I'm curious if the "shape changing" vec routine is optimized away in such
an expression. I would expect it to be, but that's just the wishful
programmer in me.
James Hague
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