Path: utzoo!utgpu!water!watmath!clyde!rutgers!labrea!decwrl!hplabs!hpda!hpesoc1!hpcllla!hpclisp!hpclscu!shankar
From: shankar@hpclscu.HP.COM (Shankar Unni)
Newsgroups: comp.lang.pascal
Subject: Re: Complex arithmetic
Message-ID: <950005@hpclscu.HP.COM>
Date: 13 Jan 88 17:50:09 GMT
References: <11219@brl-adm.ARPA>
Organization: HP ITG/ISO Computer Language Lab
Lines: 39

/ hpclscu:comp.lang.pascal / 4526P%NAVPGS.BITNET@CUNYVM.CUNY.EDU (LT Scott A. Norton, USN) /  6:42 pm  Jan 11, 1988 /

> My first gripe is that Pascal doesn't provide, or let me define, infix
> arithmetic operators for complex numbers.  Fortran has complex math
> built in, and Ada lets you define "+", for example, as an operator
> for user-defined types.

This is one among several big hits against Pascal, at least as it is defined
by the ANSI folks. Lots of other features (seperate compilation, type
coercion, pointer manipulation, extensibility, etc) are also missing.

There is an evolving standard for Extended Pascal (also by the ANSI committee)
which has most of these features, and a whole lot more (to the point where it
looks like a union of Pascal, FORTRAN and COBOL (shudder!!)). But the most
important "feature", i.e. extensibility of the language (ability to define
and overload operators, add "predefines" (inline procedures)) is still absent.

C++ (or objective C) is much better in this regard, giving the programmer the
ability to define classes of objects, and overloaded functions and operators
(a lot like ADA) to generate inline code for these types. As a starter, the
compiler comes with a few such types implemented as add-on include files, to 
give the programmer a good example to base his/her modules on. One of these,
of course, is a "complex" module.

I realise, of course, that this is no consolation to you. As Pascal stands
today (or even as it stands tomorrow, for that matter), you may have to define
"LISP-like" functions to do your stuff. BTW, most Pascals allow users to
return structures as function return values, so at least you should be able to
get rid of most of the new/dispose stuff: simply define functions like:

     function add (var c1, c2 : complex) : complex;
     ...

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Shankar Unni                                   allegra)
Unix Mail: shankar@hpda.hp.com            UUCP: ucbvax)!hplabs!hpda!shankar
                                                   sun)
(AT&T: (408) 447-5797)                          decwrl)
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