Floating-point Functions

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Floating-point Functions
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   This is a description of the *preliminary* interface for
floating-point arithmetic in GNU MP 2.

   The floating-point functions expect arguments of type `mpf_t'.

   The MP floating-point functions have an interface that is similar to
the MP integer functions.  The function prefix for floating-point
operations is `mpf_'.

   There is one significant characteristic of floating-point numbers
that has motivated a difference between this function class and other
MP function classes: the inherent inexactness of floating point
arithmetic.  The user has to specify the precision of each variable.  A
computation that assigns a variable will take place with the precision
of the assigned variable; the precision of variables used as input is
ignored.

   The precision of a calculation is defined as follows: Compute the
requested operation exactly (with "infinite precision"), and truncate
the result to the destination variable precision.  Even if the user has
asked for a very high precision, MP will not calculate with superfluous
digits.  For example, if two low-precision numbers of nearly equal
magnitude are added, the precision of the result will be limited to
what is required to represent the result accurately.

   The MP floating-point functions are *not* intended as a smooth
extension to the IEEE P754 arithmetic.  Specifically, the results
obtained on one computer often differs from the results obtained on a
computer with a different word size.
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