> Date: Mon, 30 May 2016 18:55:42 +0200 > From: Theo Buehler <[email protected]> > > On Mon, May 30, 2016 at 06:24:55PM +0200, Mark Kettenis wrote: > > > Date: Mon, 30 May 2016 15:34:04 +0200 > > > From: Joerg Sonnenberger <[email protected]> > > > > > > On Mon, May 30, 2016 at 02:16:20PM +0200, Theo Buehler wrote: > > > > It may be somewhat interesting to mention why expm1(x) = exp(x) - 1 and > > > > log1p(x) = log(1 + x) are provided and what their historical purpose is. > > > > However, as mlarkin@ put it: are any of our users of exp(3) going to > > > > seriously be asking themselves "hmm, is OpenBSD's exp compatible with > > > > BASIC on the HP-71B?" > > > > > > The wording change also changes the semantics quite a bit. The old > > > wording explained where the name came from and what the function does. > > > The new wording implies somewhat that the functions are obsolete, which > > > is far from true. > > > > Right. The function is as releveant as ever. And not only for > > "financial" calculations. The new text isn't an improvment. > > Ok, maybe the choice of the word 'historically' was suboptimal. I > didn't intend to imply irrelevance or obsolescence. Note also that this > is in the NOTES section, not in the DESCRIPTION section. > > How about this?
Sorry. No. The use of originally still implies that these functions are no longer relevant for the purpose mentioned in the sentence. It doesn't make sense without the historic context. I'd simply leave the NOTES section as-is. > Index: exp.3 > =================================================================== > RCS file: /var/cvs/src/lib/libm/man/exp.3,v > retrieving revision 1.33 > diff -u -p -r1.33 exp.3 > --- exp.3 26 Apr 2016 19:49:22 -0000 1.33 > +++ exp.3 30 May 2016 16:38:34 -0000 > @@ -139,7 +139,7 @@ function is an extended precision versio > .Pp > The > .Fn expm1 > -function computes the value exp(x)\-1 accurately even for tiny argument > +function computes the value exp(x) \(mi 1 accurately even for tiny argument > .Fa x . > The > .Fn expm1f > @@ -194,7 +194,7 @@ function is an extended precision versio > The > .Fn log1p > function computes > -the value of log(1+x) accurately even for tiny argument > +the value of log(1 + x) accurately even for tiny argument > .Fa x . > The > .Fn log1pf > @@ -277,12 +277,9 @@ are accurate enough that > .Fn pow integer integer > is exact until it is bigger than 2**53 for IEEE 754. > .Sh NOTES > -The functions exp(x)\-1 and log(1+x) are called > -expm1 and logp1 in BASIC on the Hewlett\-Packard HP-71B > -and APPLE Macintosh, EXP1 and LN1 in Pascal, exp1 and log1 in C > -on APPLE Macintoshes, where they have been provided to make > -sure financial calculations of ((1+x)**n\-1)/x, namely > -expm1(n*log1p(x))/x, will be accurate when x is tiny. > +Originally, expm1(x) = exp(x) \(mi 1 and log1p(x) = log(1 + x) > +were used to ensure financial calculations of ((1 + x)**n \(mi 1) / x, > +namely expm1(n * log1p(x)) / x, are accurate when x is tiny. > They also provide accurate inverse hyperbolic functions. > .Pp > The function > > >
