From johnreid@maths.anu.edu.au Wed Apr  1 03:04:03 1995
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Date: Tue, 28 Mar 1995 17:04:03 +1000
From: "John.Reid" <John.Reid@maths.anu.edu.au>
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To: x3j3@ncsa.uiuc.edu
Subject: Item for JOR
Cc: SC22WG5@dkuug.dk, behrman@sccm.Stanford.EDU
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Stan,
     I understand that you are now keeper of 004 (JOR). This request 
comes from the US and seems to me to be perfectly reasonable. My I ask
on Behrman's behalf that you put it in the JOR? If you need more information,
I am sure he will be pleased to oblige.

Best wishes,
JOhn.

............................................................


From behrman@sccm.Stanford.EDU Wed Mar 15 15:24:15 1995
Date: Tue, 14 Mar 1995 21:10:35 -0800
From: William Behrman <>
To: jkr@letterbox.rl.ac.uk
Content-Length: 1686


John,

    I am developing an algorithm that I wish to make available in
    standard Fortran.  Unfortunately, as things stand now, I have to
    call two math intrinsic functions that are available in the C math
    library but aren't in Fortran.

    I understand that the Fortran standards committees are currently
    discussing numerical functionality in C that Fortran is missing.
    The two functions that I mentioned are fairly well established in
    the elementary functions community (see refs 1-3) and are quite
    fundamental and important.

    The two functions are:

	exp( x ) - 1,
	log( x + 1 ).
    
    When x is small, exp and log do not calculate these functions
    accurately.

    The two functions are inverse to one another and arise rather
    naturally (in Mathematica notation):

        Integrate[ Exp[ t ], {t, 0, x} ] == Exp[ x ] - 1.
    
    I think that these two functions should be considered for inclusion
    into Fortran.

Sincerely,

William Behrman
Scientific Computing and Computational Mathematics
Stanford University


References

1)  Tang, P.T.P.  "Table-driven implementation of the expm1 function
      in IEEE floating-point arithmetic."  ACM TRANSACTIONS ON
      MATHEMATICAL SOFTWARE  (June 1992) vol.18, no.2, p. 211-22.

2)  Tang, P.T.P.  "Table-driven implementation of the logarithm
      function in IEEE floating-point arithmetic."  ACM TRANSACTIONS ON
      MATHEMATICAL SOFTWARE  (Dec. 1990) vol.16, no.4, p. 378-400.

3)  Tang, P.T.P.  "Table-driven implementation of the exponential
      function in IEEE floating-point arithmetic."  ACM TRANSACTIONS ON
      MATHEMATICAL SOFTWARE  (June 1989) vol.15, no.2, p. 144-57.