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Floating Point Rounding Mode

IEEE floating point specifies four possible rounding modes:

:nearest
In this mode, the inexact results are rounded to the nearer of the two possible result values. If the neither possibility is nearer, then the even alternative is chosen. This form of rounding is also called ``round to even'', and is the form of rounding specified for the Common Lisp round function.

:positive-infinity
This mode rounds inexact results to the possible value closer to positive infinity. This is analogous to the Common Lisp ceiling function.

:negative-infinity
This mode rounds inexact results to the possible value closer to negative infinity. This is analogous to the Common Lisp floor function.

:zero
This mode rounds inexact results to the possible value closer to zero. This is analogous to the Common Lisp truncate function.



Subsections

Peter Van Eynde 2000-02-08