Specialcase values
The following table gives the names of special cases and how each
is represented.
Value name

Sign

Exponent

Fraction




MSB

Rest of fraction

NaN (nontrapping)

X

Max

0

Nonzero

Trapping NaN

X

Max

1

X

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
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,
nonTrapping 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.
Next topic:
NaNs and infinities
Previous topic:
Maximum and minimum representable floating point values
© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7  11 February 2003