Added support for the f{maximum,minimum}_{mag,num} families, the new
C23 standard functions for maximum magnitude and number-preferring
maximum.  This includes modifying fmax.3, on top of D56230, to
recommend the use of fmaximum_num and fminimum_num.

Reviewed by:	fuz, kargl
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D56236

Starting from the existing fmax{,f,l} functions I've added the fmaximum
family, which handles NaN according to the newest standard (propagating
it).

This commit is a PoC for GSoC 2026.

Reviewed by:	fuz, kargl
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D55834

This is the *pi family of trigonometric functions. Quite a few C23
functions are still missing.  These seem to be:
acospi, acospif, acospil, asinpi, asinpif, asinpil, atan2pi, atan2pif,
atan2pil, atanpi, atanpif, atanpil, canonicalize, canonicalizef,
canonicalizel, compoundn, compoundnf, compoundnl, daddl, ddivl, dfmal,
dmull, dsqrtl, dsubl, exp10, exp10f, exp10l, exp10m1, exp10m1f,
exp10m1l, exp2m1, exp2m1f, exp2m1l, fadd, faddl, fdiv, fdivl, ffma,
ffmal, fmaximum, fmaximum_mag, fmaximum_mag_num, fmaximum_mag_numf,
fmaximum_mag_numl, fmaximum_magf, fmaximum_magl, fmaximum_num,
fmaximum_numf, fmaximum_numl, fmaximumf, fmaximuml, fminimum,
fminimum_mag, fminimum_mag_num, fminimum_mag_numf, fminimum_mag_numl,
fminimum_magf, fminimum_magl, fminimum_num, fminimum_numf,
fminimum_numl, fminimumf, fminimuml, fmul, fmull, fromfp, fromfpf,
fromfpl, fromfpx, fromfpxf, fromfpxl, fsqrt, fsqrtl, fsub, fsubl,
iscanonical, iseqsig, issignaling, issubnormal, iszero, nextdown,
nextdownf, nextdownl, nextup, nextupf, nextupl, pown, pownf, pownl,
powr, powrf, powrl, rootf, rootl, rootn, roundeven, roundevenf,
roundevenl, rsqrt, rsqrtf, rsqrtl, ufromfp, ufromfpf, ufromfpl,
ufromfpx, ufromfpxf, ufromfpxl.

Reviewed by:	imp
Approved by:	markj (mentor)
MFC after:	1 month
Relnotes:	yes
Differential Revision:	https://reviews.freebsd.org/D53783

Make sure the entirety of x is zero before flipping the sign bit.
Otherwise the sign would be wrong for small values of x when x is
negative and |n*y| > |x|

Reported by:	alfredo
PR:		251091
Reviewed by:	kargl
MFC after:	3 days
Differential Revision: https://reviews.freebsd.org/D53023

PR:	289447
MFC after:	1 week

Follow-up commit d180086e6eae by fixing the left shift of signed integer
entities through the use of a helper function. Specific per file changes
are:

* lib/msun/src/e_fmodf.c:
* lib/msun/src/s_remquof.c:
  . Eliminate now unused variable 'i'.
  . Sort declaration statement.
  . Use subnormal_ilogbf() to avoid left shift of signed integer.

* lib/msun/src/math_private.h b/lib/msun/src/math_private.h:
  . Implement subnormal_ilogbf() to extract an exponent of a subnormal
    float.  This avoids left shifts of signed integers.
  . Update nearby comment.

* lib/msun/src/s_ilogbf.c
  . Fix declaration of the function statement in accordance with style(9).
  . Use subnormal_ilogbf() to avoid left shift of signed integer.

PR:		288850
MFC after:	1 week

The patch fixes a few instances of left shifts on
signed integer entities.  A 'static inline' helper function
'subnormal_ilogb()' has been added to math_private.h.  This
function is then used e_fmod.c, s_ilogb(), and s_remquo.c.

The change in s_remquo.c has only been compile tested.

The change to e_fmod.c has been test on over 3 billion pairs
of subnormal numbers where testing included x > y and x < y
pairs.  The test compared the output from fmod() with the
output from mpfr_fmod() from MPFR.  There were no difference.

The change to s_ilogb() has had limited testing where its
output was compared against frexp().  In this testing, no
differences in output were detected.

PR:	288778
MFC after:	1 week

* lib/msun/src/s_ccosh.c:
  . Update Copyright years.
  . sin() and cos() are needed at the same time, so use sincos() to
    compute values.  This does argument reduction once instead of twice.
  . Replace '* 0.5' with '/ 2'. This reduces diff with s_ccoshf.c.
  . For (LDBL_MANT_DIG == 53), add weak references for ccoshl and ccosl.

* lib/msun/src/s_ccoshf.c:
  . Update Copyright years.
  . sin() and cos() are needed at the same time, so use sincos() to
    compute values.  This does argument reduction once instead of twice.
  . Replace '* 0.5F' with '/ 2'. This reduces diff with s_ccoshf.c.

* lib/msun/src/s_csinh.c:
  . Update Copyright years.
  . sin() and cos() are needed at the same time, so use sincos() to
    compute values.  This does argument reduction once instead of twice.
  . Replace '* 0.5' with '/ 2'. This reduces diff with s_csinhf.c.
  . For (LDBL_MANT_DIG == 53), add weak references for csinhl and csinl.

* lib/msun/src/s_csinhf.c:
  . Update Copyright years.
  . sin() and cos() are needed at the same time, so use sincos() to
    compute values.  This does argument reduction once instead of twice.
  . Replace '* 0.5F' with '/ 2'. This reduces diff with s_ccoshf.c.

PR:		288740
MFC after:	1 week

These headers relied in __BEGIN_DECS/__END_DECLS being defined when
sys/_types.h was included, but there's not a requirement that this be
the case.

Reviewed by:	imp
Exp-run by:	antoine (PR 286274)
Pull Request:	https://github.com/freebsd/freebsd-src/pull/1595

Since we're inverting a cube, we have:
    f(Tₙ)=Tₙ³-x    (1)

Its first and second derivatives are:
    f'(Tₙ)=3Tₙ²    (2)
    f"(Tₙ)=6Tₙ     (3)

Halley iteration[1] uses:
    Tₙ₊₁=Tₙ-2f(Tₙ)f'(Tₙ)/(2f'(Tₙ)²-f(Tₙ)f"(Tₙ))    (4)

Replacing the terms of (4) using (1), (2) and (3):

Tₙ₊₁ = Tₙ-2f(Tₙ)f'(Tₙ)/(2f'(Tₙ)²-f(Tₙ)f"(Tₙ))
     = Tₙ-2(Tₙ³-x)3Tₙ²/(2(3Tₙ²)²-(Tₙ³-x)6Tₙ)
     = <snip, see WolframAlpha[2] alternate forms>
     = Tₙ(2x+Tₙ³)/(x+2Tₙ³)

This formula corresponds to the exact expression used in the code.

Newton formula is Tₙ-f(Tₙ)/f'(Tₙ) which would have simplified to
(2Tₙ³+x)/(3Tₙ²) instead.

[1] https://en.wikipedia.org/wiki/Halley's_method
[2] https://www.wolframalpha.com/input?i=T-2%28T%5E3-x%293T%5E2%2F%282%283T%5E2%29%5E2-%28T%5E3-x%296T%29

Note: UTF8 in commit message due to the heavy math being hard to
recreate w/o it. -- imp

Signed-off-by: Clément Bœsch <u@pkh.me>
Reviewed by: imp
Pull Request: https://github.com/freebsd/freebsd-src/pull/1684