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| -rw-r--r-- | doc/mpfr.texi | 24 |
1 files changed, 15 insertions, 9 deletions
diff --git a/doc/mpfr.texi b/doc/mpfr.texi index 6cdf59e22..16ae493e4 100644 --- a/doc/mpfr.texi +++ b/doc/mpfr.texi @@ -664,15 +664,21 @@ A @dfn{floating-point number}, or @dfn{float} for short, is an object representing a radix-2 floating-point number consisting of a sign, an arbitrary-precision normalized significand (also called mantissa), and an exponent (an integer in some given range); these are called -@dfn{regular numbers}. Like in the IEEE@tie{}754 standard, a floating-point -number can also have three kinds of special values: a signed zero, a -signed infinity, and Not-a-Number (NaN)@. NaN can represent the default -value of a floating-point object and the result of some operations for -which no other results would make sense, such as 0 divided by 0 or -+Infinity minus +Infinity; unless documented otherwise, the sign bit of -a NaN is unspecified. Note that contrary to IEEE@tie{}754, MPFR has a single -kind of NaN and does not have subnormals. Other than that, the behavior -is very similar to IEEE@tie{}754, but there may be some differences. +@dfn{regular numbers}. By convention, the radix point of the significand +is just before the first digit (which is always 1 due to normalization), +like in the C language, but unlike in IEEE@tie{}754 (thus, for a given +number, the exponent values in MPFR and in IEEE@tie{}754 differ by 1). + +Like in the IEEE@tie{}754 standard, a floating-point number can also +have three kinds of special values: a signed zero (+0 or @minus{}0), +a signed infinity (+Inf or @minus{}Inf), and Not-a-Number (NaN)@. NaN +can represent the default value of a floating-point object and the +result of some operations for which no other results would make sense, +such as 0 divided by 0 or +Infinity minus +Infinity; unless documented +otherwise, the sign bit of a NaN is unspecified. Note that contrary to +IEEE@tie{}754, MPFR has a single kind of NaN and does not have subnormals. +Other than that, the behavior is very similar to IEEE@tie{}754, but there +are some minor differences. The C data type for such objects is @code{mpfr_t}, internally defined as a one-element array of a structure (so that when passed as an |