FOUNDATION SERVICES - Signaling NaNs

Signaling NaNs

Quiet NaNs propagate through operations except comparisons without raising exceptions. See "Comparisons" on page 226.
Signaling NaNs raise the invalid flag whenever they arise in an operation other than assignment with no change of format.

Signaling NaNs operate in conjunction with trapping. An application can, in principle, use bits of the significand to encode information to be processed by a trap handler whenever a signaling NaN is encountered. Because trapping has not found wide acceptance, however, neither have signaling NaNs.

CommonPoint systems support quiet NaNs only. If a signaling NaN appears in an arithmetic operation, the operation raises invalid and delivers a quiet NaN result.

NOTE The standards do not specify how quiet and signaling NaNs are distinguished by their signifcands. It is possible for quiet NaNs created by one CommonPoint platform could be signaling NaNs when received as input by another.

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