Special-case values

The following table gives the names of special cases and how each is represented.

Single and Double Precision:

Value Name	Sign	Exponent	Fraction
			MSB	Rest of Fraction
NaN (non-trapping)	X	Max	1	X
Trapping NaN	X	Max	0	Nonzero
Positive Infinity	0	Max	Min
Negative Infinity	1	Max	Min
Positive Zero	0	Min	Min
Negative Zero	1	Min	Min
Denormalized Number	X	Min	Nonzero
Normalized Number	X	NotMM	X

Key:

X

does not matter

Max

maximum value that can be stored in the field (all 1's)

Min

minimum value that can be stored in the field (all 0's)

NaN

not a number

NotMM

field is not equal to either Min or Max values

Nonzero

field contains at least one ``1'' bit

MSB

Most Significant Bit

Value Name	Sign	Exponent	Fraction
			MSB
Rest of Fraction
NaN (non-trapping)	X	Max	1	Nonzero
Trapping NaN	X	Max	0	Nonzero
Positive Infinity	0	Max	1	Min
Negative Infinity	1	Max	1	Min
Positive Zero	0	Min	Min
Negative Zero	1	Min	Min
Denormalized Number	X	Min	0	Nonzero
Normalized Number	X	NotMM	1	X

The algorithm for classification of a value into special cases follows:

If (Exponent==Max)
If (Fraction==Min)
Then the number is Infinity (Positive or Negative
as determined by the Sign bit).
Else the number is NaN (Trapping if FractionMSB==0,
non-Trapping if FractionMSB==1).

Else If (Exponent==Min)
If (Fraction==Min)
Then the number is Zero (Positive or Negative
as determined by the Sign bit).
Else the number is Denormalized.
Else the number is Normalized.