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The following types and functions were mainly designed for the implementation of MPFR, but may be useful for users too. However no upward compatibility is guaranteed. You may need to include mpfr-impl.h to use them.
The mpfr_t
type consists of four fields.
_mpfr_prec
field is used to store the precision of
the variable (in bits); this is not less than MPFR_PREC_MIN
.
_mpfr_sign
field is used to store the sign of the variable.
_mpfr_exp
field stores the exponent.
An exponent of 0 means a radix point just above the most significant
limb. Non-zero values n are a multiplier 2^n relative to that
point.
A NaN, an infinity and a zero are indicated by a special value of the exponent.
_mpfr_d
is a pointer to the limbs, least
significant limbs stored first.
The number of limbs in use is controlled by _mpfr_prec
, namely
ceil(_mpfr_prec
/mp_bits_per_limb
).
Non-singular values always have the most significant bit of the most
significant limb set to 1. When the precision does not correspond to a
whole number of limbs, the excess bits at the low end of the data are zero.