initial import of MPFR 4.2.0. changes from 4.1.0 include:

Binary compatible with MPFR 4.0.* and 4.1.*, though some minor changes
in the behavior of the formatted output functions may be visible,
regarded as underspecified behavior or bug fixes (see below).

New functions mpfr_cosu, mpfr_sinu, mpfr_tanu, mpfr_acosu, mpfr_asinu,
mpfr_atanu and mpfr_atan2u.

New functions mpfr_cospi, mpfr_sinpi, mpfr_tanpi, mpfr_acospi,
mpfr_asinpi, mpfr_atanpi and mpfr_atan2pi.

New functions mpfr_log2p1, mpfr_log10p1, mpfr_exp2m1, mpfr_exp10m1 and
mpfr_compound_si.

New functions mpfr_fmod_ui, mpfr_powr, mpfr_pown, mpfr_pow_uj,
mpfr_pow_sj and mpfr_rootn_si (mpfr_pown is actually a macro defined as
an alias for mpfr_pow_sj).

Bug fixes.
- In particular, for the formatted output functions (mpfr_printf, etc.),
the case where the precision consists only of a period has been fixed to
be like .0 as specified in the ISO C standard, and the manual has been
corrected and clarified.
- The macros of the custom interface have also been fixed:
they now behave like functions (except a minor limitation for
mpfr_custom_init_set).

GNU mpfr 4.1.0. main changes from 4.0:

Changed __float128 to the type _Float128 specified in ISO/IEC TS 18661.
__float128 is used as a fallback if _Float128 is not supported.
New function mpfr_get_str_ndigits about conversion to a string of digits.
New function mpfr_dot for the dot product (incomplete, experimental).
New functions mpfr_get_decimal128 and mpfr_set_decimal128 (available
only when MPFR has been built with decimal float support).
New function mpfr_cmpabs_ui.
New function mpfr_total_order_p for the IEEE 754 totalOrder predicate.
The mpfr_out_str function now accepts bases from -2 to -36, in order to
follow mpfr_get_str and GMP's mpf_out_str functions (these cases gave an
assertion failure, as with other invalid bases).
Shared caches: cleanup; really detect lock failures (abort in this case).
Improved mpfr_add and mpfr_sub when all operands have a precision
equal to twice the number of bits per word, e.g., 128 bits on a 64-bit
platform.
Optimized the tuning parameters for various architectures.

branches: 1.1.1.1.2; 1.1.1.1.4;
import mpfr 4.0.1. main changes since 3.1.5 are:

Changes from version 4.0.0 to version 4.0.1:
- Bug fixes (see ChangeLog file), in particular in mpfr_div_ui, which
could yield an incorrectly rounded result to nearest when using
different precisions; this bug had been present since the introduction
of mpfr_div_ui, and in MPFR 4.0.0, it was affecting mpfr_div too.

Changes from versions 3.1.* to version 4.0.0:
- Partial support of MPFR_RNDF (faithful rounding).
- New functions: mpfr_fpif_export and mpfr_fpif_import to export and import
numbers in a floating-point interchange format, independent both on the
number of bits per word and on the endianness.
- New function mpfr_fmodquo to return the low bits of the quotient
corresponding to mpfr_fmod.
- New functions mpfr_flags_clear, mpfr_flags_set, mpfr_flags_test,
mpfr_flags_save and mpfr_flags_restore to operate on groups of flags.
- New functions mpfr_set_float128 and mpfr_get_float128 to convert from/to
the __float128 type (requires --enable-float128 and compiler support).
- New functions mpfr_buildopt_float128_p and mpfr_buildopt_sharedcache_p.
- New functions mpfr_rint_roundeven and mpfr_roundeven, completing the
other similar round-to-integer functions for rounding to nearest with
the even-rounding rule.
- New macro mpfr_round_nearest_away to add partial emulation of the
rounding to nearest-away (as defined in IEEE 754-2008).
- New functions mpfr_nrandom and mpfr_erandom to generate random numbers
following normal and exponential distributions respectively.
- New functions mpfr_fmma and mpfr_fmms to compute a*b+c*d and a*b-c*d.
- New function mpfr_rootn_ui, similar to mpfr_root, but agreeing with the
rootn function of the IEEE 754-2008 standard.
- New functions mpfr_log_ui to compute the logarithm of an integer,
mpfr_gamma_inc for the incomplete Gamma function.
- New function mpfr_beta for the Beta function (incomplete, experimental).
- New function mpfr_get_q to convert a floating-point number into rational.
- Dropped K&R C compatibility.
- Major speedup in mpfr_add, mpfr_sub, mpfr_mul, mpfr_div and mpfr_sqrt when
all operands have the same precision and this precision is less than twice
the number of bits per word, e.g., less than 128 on a 64-bit computer.
- Speedup by a factor of almost 2 in the double <--> mpfr conversions
(mpfr_set_d and mpfr_get_d).
- Speedup in mpfr_log1p and mpfr_atanh for small arguments.
- Speedup in the mpfr_const_euler function (contributed by Fredrik Johansson),
in the computation of Bernoulli numbers (used in mpfr_gamma, mpfr_li2,
mpfr_digamma, mpfr_lngamma and mpfr_lgamma), in mpfr_div, in mpfr_fma
and mpfr_fms.

GNU mpfr 4.1.0. main changes from 4.0:

Changed __float128 to the type _Float128 specified in ISO/IEC TS 18661.
__float128 is used as a fallback if _Float128 is not supported.
New function mpfr_get_str_ndigits about conversion to a string of digits.
New function mpfr_dot for the dot product (incomplete, experimental).
New functions mpfr_get_decimal128 and mpfr_set_decimal128 (available
only when MPFR has been built with decimal float support).
New function mpfr_cmpabs_ui.
New function mpfr_total_order_p for the IEEE 754 totalOrder predicate.
The mpfr_out_str function now accepts bases from -2 to -36, in order to
follow mpfr_get_str and GMP's mpf_out_str functions (these cases gave an
assertion failure, as with other invalid bases).
Shared caches: cleanup; really detect lock failures (abort in this case).
Improved mpfr_add and mpfr_sub when all operands have a precision
equal to twice the number of bits per word, e.g., 128 bits on a 64-bit
platform.
Optimized the tuning parameters for various architectures.

branches: 1.1.1.1.2; 1.1.1.1.4;
import mpfr 4.0.1. main changes since 3.1.5 are:

Changes from version 4.0.0 to version 4.0.1:
- Bug fixes (see ChangeLog file), in particular in mpfr_div_ui, which
could yield an incorrectly rounded result to nearest when using
different precisions; this bug had been present since the introduction
of mpfr_div_ui, and in MPFR 4.0.0, it was affecting mpfr_div too.

Changes from versions 3.1.* to version 4.0.0:
- Partial support of MPFR_RNDF (faithful rounding).
- New functions: mpfr_fpif_export and mpfr_fpif_import to export and import
numbers in a floating-point interchange format, independent both on the
number of bits per word and on the endianness.
- New function mpfr_fmodquo to return the low bits of the quotient
corresponding to mpfr_fmod.
- New functions mpfr_flags_clear, mpfr_flags_set, mpfr_flags_test,
mpfr_flags_save and mpfr_flags_restore to operate on groups of flags.
- New functions mpfr_set_float128 and mpfr_get_float128 to convert from/to
the __float128 type (requires --enable-float128 and compiler support).
- New functions mpfr_buildopt_float128_p and mpfr_buildopt_sharedcache_p.
- New functions mpfr_rint_roundeven and mpfr_roundeven, completing the
other similar round-to-integer functions for rounding to nearest with
the even-rounding rule.
- New macro mpfr_round_nearest_away to add partial emulation of the
rounding to nearest-away (as defined in IEEE 754-2008).
- New functions mpfr_nrandom and mpfr_erandom to generate random numbers
following normal and exponential distributions respectively.
- New functions mpfr_fmma and mpfr_fmms to compute a*b+c*d and a*b-c*d.
- New function mpfr_rootn_ui, similar to mpfr_root, but agreeing with the
rootn function of the IEEE 754-2008 standard.
- New functions mpfr_log_ui to compute the logarithm of an integer,
mpfr_gamma_inc for the incomplete Gamma function.
- New function mpfr_beta for the Beta function (incomplete, experimental).
- New function mpfr_get_q to convert a floating-point number into rational.
- Dropped K&R C compatibility.
- Major speedup in mpfr_add, mpfr_sub, mpfr_mul, mpfr_div and mpfr_sqrt when
all operands have the same precision and this precision is less than twice
the number of bits per word, e.g., less than 128 on a 64-bit computer.
- Speedup by a factor of almost 2 in the double <--> mpfr conversions
(mpfr_set_d and mpfr_get_d).
- Speedup in mpfr_log1p and mpfr_atanh for small arguments.
- Speedup in the mpfr_const_euler function (contributed by Fredrik Johansson),
in the computation of Bernoulli numbers (used in mpfr_gamma, mpfr_li2,
mpfr_digamma, mpfr_lngamma and mpfr_lgamma), in mpfr_div, in mpfr_fma
and mpfr_fms.

branches: 1.1.1.1.2;
import mpfr 4.0.1. main changes since 3.1.5 are:

Changes from version 4.0.0 to version 4.0.1:
- Bug fixes (see ChangeLog file), in particular in mpfr_div_ui, which
could yield an incorrectly rounded result to nearest when using
different precisions; this bug had been present since the introduction
of mpfr_div_ui, and in MPFR 4.0.0, it was affecting mpfr_div too.

Changes from versions 3.1.* to version 4.0.0:
- Partial support of MPFR_RNDF (faithful rounding).
- New functions: mpfr_fpif_export and mpfr_fpif_import to export and import
numbers in a floating-point interchange format, independent both on the
number of bits per word and on the endianness.
- New function mpfr_fmodquo to return the low bits of the quotient
corresponding to mpfr_fmod.
- New functions mpfr_flags_clear, mpfr_flags_set, mpfr_flags_test,
mpfr_flags_save and mpfr_flags_restore to operate on groups of flags.
- New functions mpfr_set_float128 and mpfr_get_float128 to convert from/to
the __float128 type (requires --enable-float128 and compiler support).
- New functions mpfr_buildopt_float128_p and mpfr_buildopt_sharedcache_p.
- New functions mpfr_rint_roundeven and mpfr_roundeven, completing the
other similar round-to-integer functions for rounding to nearest with
the even-rounding rule.
- New macro mpfr_round_nearest_away to add partial emulation of the
rounding to nearest-away (as defined in IEEE 754-2008).
- New functions mpfr_nrandom and mpfr_erandom to generate random numbers
following normal and exponential distributions respectively.
- New functions mpfr_fmma and mpfr_fmms to compute a*b+c*d and a*b-c*d.
- New function mpfr_rootn_ui, similar to mpfr_root, but agreeing with the
rootn function of the IEEE 754-2008 standard.
- New functions mpfr_log_ui to compute the logarithm of an integer,
mpfr_gamma_inc for the incomplete Gamma function.
- New function mpfr_beta for the Beta function (incomplete, experimental).
- New function mpfr_get_q to convert a floating-point number into rational.
- Dropped K&R C compatibility.
- Major speedup in mpfr_add, mpfr_sub, mpfr_mul, mpfr_div and mpfr_sqrt when
all operands have the same precision and this precision is less than twice
the number of bits per word, e.g., less than 128 on a 64-bit computer.
- Speedup by a factor of almost 2 in the double <--> mpfr conversions
(mpfr_set_d and mpfr_get_d).
- Speedup in mpfr_log1p and mpfr_atanh for small arguments.
- Speedup in the mpfr_const_euler function (contributed by Fredrik Johansson),
in the computation of Bernoulli numbers (used in mpfr_gamma, mpfr_li2,
mpfr_digamma, mpfr_lngamma and mpfr_lgamma), in mpfr_div, in mpfr_fma
and mpfr_fms.