X3J3/96-165
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Date:     November 11, 1996
To:       X3J3
From:	    Loren Meissner
Subject:	 Minor Technical Enhancement M6: Revisited

At Meeting 138, X3J3 approved (8-4) addition of a few conversion
intrinsics (INT, REAL, DBLE, and CMPLX) to the list of functions
permitted in an Initialization Exression. (This position evolved
over a few meetings as a preferred alternative to creating a new
sort of complex constant that is partly literal constant and partly
named constant.)

Subsequently, it has been suggested that further intrinsic functions
be permitted in initialization expressions. I sent an email message
to X3J3 in early October asking for opinions on this question. I
received a few replies, all favoring extension in this area. Later,
a posting on comp-fortran-90 questioned why ATAN, SIN, etc. should
not be permitted.

I have identified five possible levels for extension. (The only
intrinsics at question are the elementals; others except ALLOCATABLE
are already permitted.)

1.  As in Fortran 95: permit only those elemental intrinsics that
    have arguments and results of integer or character type;

2.  As "approved" at meeting 138, add INT, REAL, DBLE, and CMPLX

3.  As above PLUS all other conversion intrinsics: AIMAG, AINT,
    ANINT, CEILING, FLOOR, and NINT;

4.  All elemental itrinsics EXCEPT the math functions ABS(z), ACOS,
    ASIN, ATAN, ATAN2, COS, COSH, EXP, LOG, LOG10, SIN, SINH, SQRT,
    TAN, TANH;

5.  All elemental intrinsics

NOTE that F95 added all elemental intrinsics to the list for Speci-
fication Expressions, along with user-defined PURE functions.

CONCERNS:

Traditionally, an objection to level 5 has been that the compiler
should not be required to have access to the math library. Responses
to my positings indicate that this is no longer a major concern.

Another problem is cross compilation: a small computer might have
trouble simulating complicated operations for initialization on a
larger computer, for example.

POSSIBLE STRAW VOTE: Should extension go to level 3, 4, or 5 as
listed above?