Re: MODULEand USE versus Argument Passing

In article <d9us2s$ncr$1@xxxxxxxxxxxxxxxxxx>,
E. Robert Tisdale <E.Robert.Tisdale@xxxxxxxxxxxx> wrote:
>
>Global variables are *always* a bad idea.
>Never pass function arguments through modules or common storage.

Really? Suppose I am using one of the NAG routines, e.g. d01akf, to
calculate integral from a to b of f(x,y) dx for various values of y.
The NAG specification says (irrelevant detail omitted; and REAL should
be replaced by REAL(kind(1.0d0)) with many compilers)

SUBROUTINE d01akf(f,a,b, ...)
REAL f,a,b, ...
EXTERNAL f

and f must be declared as EXTERNAL in the (sub)program from which
d01akf is called, and it must be declared as a REAL(DP) function of
one REAL(DP) variable, not two.

I had thought the way to get y into f was by COMMON before f90, and by
using a module nowadays. What would Robert have me do?

In www.nag.com/numeric/fl/manual/pdf/D01/d01akf.pdf is NAG's manual
for d01akf; its example of how to use d01akf uses an integer variable
in COMMON to count the number of evaluations of the function f.

John Harper, School of Mathematics, Statistics and Computer Science,
Victoria University, PO Box 600, Wellington, New Zealand
e-mail john.harper@xxxxxxxxx phone (+64)(4)463 5341 fax (+64)(4)463 5045
.