Arithmetic Operations on Exceptional Values

This section describes the results derived from applying the basic arithmetic operations to combinations of exceptional and ordinary floating-point values. The information that follows assumes that no traps or any other exception actions are taken.

The following tables explain the abbreviations:

Table A-16 Abbreviation Usage

Abbreviation	Meaning
Num	Subnormal or normal number
Inf	Infinity (positive or negative)
NaN	Not a number
Uno	Unordered

The tables that follow describe the types of values that result from arithmetic operations performed with combinations of different types of operands.

Table A-17 Addition and Subtraction Results

	Right Operand
Left Operand	0	Num	Inf	NaN
0	0	Num	Inf	NaN
Num	Num	See Note	Inf	NaN
Inf	Inf	Inf	See Note	NaN
NaN	NaN	NaN	NaN	NaN

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Note -

Num + Num could be Inf, rather than Num, when the result is too large (overflow). Inf + Inf = NaN when the infinities are of opposite sign.

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Table A-18 Multiplication Results

	Right Operand
Left Operand	0	Num	Inf	NaN
0	0	0	NaN	NaN
Num	0	Num	Inf	NaN
Inf	NaN	Inf	Inf	NaN
NaN	NaN	NaN	NaN	NaN

Table A-19 Division Results

	Right Operand
Left Operand	0	Num	Inf	NaN
0	NaN	0	0	NaN
Num	Inf	Num	0	NaN
Inf	Inf	Inf	NaN	NaN
NaN	NaN	NaN	NaN	NaN

Table A-20 Comparison Results

	Right Operand
Left Operand	0	+Num	+Inf	NaN
0	=	<	<	Uno
+Num	>	The result of the comparison	<	Uno
+Inf	>	>	=	Uno
NaN	Uno	Uno	Uno	Uno

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Note -

NaN compared with NaN is unordered, and results in inequality. +0 compares equal to -0.

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