The following functions have changed after MPFR 2.2. Changes can affect the behavior of code written for some MPFR version when built and run against another MPFR version (older or newer), as described below.
mpfr_check_range changed in MPFR 2.3.2 and MPFR 2.4.
If the value is an inexact infinity, the overflow flag is now set
(in case it was lost), while it was previously left unchanged.
This is really what is expected in practice (and what the MPFR code
was expecting), so that the previous behavior was regarded as a bug.
Hence the change in MPFR 2.3.2.
mpfr_get_f changed in MPFR 3.0.
This function was returning zero, except for NaN and Inf, which do not
exist in MPF. The erange flag is now set in these cases,
and mpfr_get_f now returns the usual ternary value.
mpfr_get_si, mpfr_get_sj, mpfr_get_ui
and mpfr_get_uj changed in MPFR 3.0.
In previous MPFR versions, the cases where the erange flag
is set were unspecified.
mpfr_get_z changed in MPFR 3.0.
The return type was void; it is now int, and the usual
ternary value is returned. Thus programs that need to work with both
MPFR 2.x and 3.x must not use the return value. Even in this case,
C code using mpfr_get_z as the second or third term of
a conditional operator may also be affected. For instance, the
following is correct with MPFR 3.0, but not with MPFR 2.x:
bool ? mpfr_get_z(...) : mpfr_add(...);
On the other hand, the following is correct with MPFR 2.x, but not with MPFR 3.0:
bool ? mpfr_get_z(...) : (void) mpfr_add(...);
Portable code should cast mpfr_get_z(...) to void to
use the type void for both terms of the conditional operator,
as in:
bool ? (void) mpfr_get_z(...) : (void) mpfr_add(...);
Alternatively, if ... else can be used instead of the
conditional operator.
Moreover the cases where the erange flag is set were unspecified in MPFR 2.x.
mpfr_get_z_exp changed in MPFR 3.0.
In previous MPFR versions, the cases where the erange flag
is set were unspecified.
Note: this function has been renamed to mpfr_get_z_2exp
in MPFR 3.0, but mpfr_get_z_exp is still available for
compatibility reasons.
mpfr_strtofr changed in MPFR 2.3.1 and MPFR 2.4.
This was actually a bug fix since the code and the documentation did
not match. But both were changed in order to have a more consistent
and useful behavior. The main changes in the code are as follows.
The binary exponent is now accepted even without the 0b or
0x prefix. Data corresponding to NaN can now have an optional
sign (such data were previously invalid).
mpfr_strtofr changed in MPFR 3.0.
This function now accepts bases from 37 to 62 (no changes for the other
bases). Note: if an unsupported base is provided to this function,
the behavior is undefined; more precisely, in MPFR 2.3.1 and later,
providing an unsupported base yields an assertion failure (this
behavior may change in the future).
mpfr_subnormalize changed in MPFR 3.1.
This was actually regarded as a bug fix. The mpfr_subnormalize
implementation up to MPFR 3.0.0 did not change the flags. In particular,
it did not follow the generic rule concerning the inexact flag (and no
special behavior was specified). The case of the underflow flag was more
a lack of specification.
mpfr_urandom and mpfr_urandomb changed in MPFR 3.1.
Their behavior no longer depends on the platform (assuming this is also
true for GMP's random generator). As a consequence, the returned values
can be different between MPFR 3.1 and previous MPFR versions.
Note: as the reproducibility of these functions was not specified
before MPFR 3.1, the MPFR 3.1 behavior is not regarded as
backward incompatible with previous versions.