Newsgroups: comp.lang.misc
Path: utzoo!utgpu!news-server.csri.toronto.edu!helios.physics.utoronto.ca!alchemy.chem.utoronto.ca!mroussel
From: mroussel@alchemy.chem.utoronto.ca (Marc Roussel)
Subject: Re: Learning other languages (Was: Fortran vs. C for numerical work)
Message-ID: <1990Dec7.174243.29683@alchemy.chem.utoronto.ca>
Organization: Department of Chemistry, University of Toronto
References: <13457@chaph.usc.edu> <8960031@hpfcso.HP.COM>
Date: Fri, 7 Dec 90 17:42:43 GMT

In article <8960031@hpfcso.HP.COM> mjs@hpfcso.HP.COM (Marc Sabatella) writes:
>>     C on the other hand was not designed for math.  It was designed for
>>systems programming and any other use is incidental.  It's not so much
>>that C is difficult, it's that its syntax is unnatural for scientific
>>programming.  C is a lovely language if you're writing an OS.  I think
>>that those of us who say that we don't want to learn C because it's
>>"difficult" really mean this: C is not particularly well-suited to our
>>purposes so that beating our problem into C would be quite a chore.
>
>But what makes you say this?  About the only significant difference in syntax
>(as far as translating mathemetical formulae) is that C has no exponentiation
>operator; instead you must call a library function.  Other than that, why is
>
>	C = SQRT( SIN(X) + LOG(Y) )
>
>perceived to be more "natural" than
>
>	c = sqrt( sin(x) + log(y) );

The two lines you have written make it look like it's not a big deal.
However, consider the case where x,y and c are complex.  Then in Fortran
I simply put

      COMPLEX C,X,Y

in the declaration section of my program and the compiler does the rest,
right down to selecting the right sqrt, sin and log routines for complex
values.  On the other hand, in C I would have to supply:

     a) the complex type
     b) the addition operator for complex numbers
     c) sqrt, sin and log for complex arguments

on top of which I would have to write

c = csqrt(cadd(csin(x),clog(y)))

which, at least in my opinion, obscures the meaning much more than the
form above.  Creating a complex type in C is not a particularly big
deal, nor is writing an addition function, but providing a whole complex
library could be a lot of work.  Sure you only have to do it once and
perhaps not even that since someone else might make his code available
to you... But what's the point since Fortran knows all about complex types?
     And what about array operations?  My impression was that C's array
handling was less than impressive.  Pointers are fine, but they don't
represent a vector in as obvious a way as a one-dimensional array.
Passing a pointer to an array to a subroutine is just not quite the same
as passing a vector to a subroutine that deals with vectors.  A similar
argument applies to higher order tensors.
     If scientific programming never involved anything more than simple
algebraic operations on scalar real numbers and integers, I'd be less
resistant to the idea that C might be just as good as Fortran for this
purpose.  Unfortunately, practically all Fortran code involves matrices
or complex numbers.  Writing the same programs in C would just not be as
easy.

				Marc R. Roussel
                                mroussel@alchemy.chem.utoronto.ca