Editing IEEE 754-1985 (section)

== Representation of non-numbers ==

The biased-exponent field is filled with all 1 bits to indicate either infinity or an invalid result of a computation.

=== Positive and negative infinity ===

[[Extended real line|Positive and negative infinity]] are represented thus:

: ''sign'' = 0 for positive infinity, 1 for negative infinity.
: ''biased exponent'' = all 1 bits.
: ''fraction'' = all 0 bits.

=== NaN ===

Some operations of [[Floating-point arithmetic#Floating-point operations|floating-point arithmetic]] are invalid, such as taking the square root of a negative number. The act of reaching an invalid result is called a floating-point ''exception.'' An exceptional result is represented by a special code called a NaN, for "[[Not a Number]]". All NaNs in IEEE&nbsp;754-1985 have this format:

: ''sign'' = either 0 or 1.
: ''biased exponent'' = all 1 bits.
: ''fraction'' = anything except all 0 bits (since all 0 bits represents infinity).