Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!iuvax!purdue!mentor.cc.purdue.edu!pur-ee!pur-phy!hal
From: hal@pur-phy (Hal Chambers)
Newsgroups: comp.lang.pascal
Subject: Re: complex numbers
Message-ID: <2360@pur-phy>
Date: 14 Jul 89 11:40:25 GMT
References: <2751@ohstpy.mps.ohio-state.edu>
Reply-To: hal@newton.physics.purdue.edu.UUCP (Hal Chambers)
Organization: Purdue Univ. Physics Dept., W. Lafayette, IN
Lines: 34

In article <2751@ohstpy.mps.ohio-state.edu> heff@ohstpy.mps.ohio-state.edu writes:
>. . . to write equations in source code such as
>                     a =: b + c;
>                     a := (b+c)/(d+e);
>as can be done in fortran.  For that matter, are there any languages beside
>fortran which allow easy computation of complex numbers?

This is allowed in Ada.  Besides defining the type Complex, Ada allows
programmers to define functions named "+", "/", etc. (and if I remember
correctly, these functions can be defined as "INLINE" so that the code
is generated in place).  The compiler determines which "+" function to
use from the types of the operands.  To be complete, be sure to define
the operators for mixed-mode expressions (complex + real, real + complex,
etc.).

Although Pascal (and Modula-2, etc.) allows the definition of a Complex
type,  there is no way for the programmer to define the operators
other than as explicit procedure calls (functions can't return a
structured type).

So the examples above would appear as something like:
    >   a =: b + c;
		cadd(a, b,c);

    >   a := (b+c)/(d+e);
		cadd(c1, b,c);
		cadd(c2, d,e);
		cdiv(a, c1,c2);
Ugly!!!!

-- 
Hal Chambers
hal@newton.physics.purdue.edu
hal@physics-newton.arpa