Scieneer Common Lisp 1.3.9 online documentation

ext:set-floating-point-modes &key traps rounding-mode current-exceptions accrued-exceptions fast-mode[Function]

This function sets options controlling the floating-point hardware. If a keyword is not supplied, then the current value is preserved. Possible keywords:

A list of the exception conditions that should cause traps. Possible exceptions are :underflow, :overflow, :inexact, :invalid, :divide-by-zero, and on the X86 and AMD64 :denormalized-operand. Initially all traps except :inexact are enabled.
The rounding mode to use when the result is not exact. Possible values are :nearest, :positive-infinity, :negative-infinity and :zero. Initially, the rounding mode is :nearest.
:current-exceptions :accrued-exceptions
These arguments allow setting of the exception flags. The main use is setting the accrued exceptions to nil to clear them.
Set the hardware's "fast mode" flag, if any. When set, IEEE conformance or debuggability may be impaired. Some machines may not have this feature, in which case the value is always nil.

get-floating-point-modes may be used to find the floating point modes currently in effect.