Special-case 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 (non-trapping)
|
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,
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.
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