This section describes the results of basic arithmetic operations with extreme and ordinary values. We assume all inputs are positive, and no traps, overflow, underflow, or other exceptions happen.
Table C3 Extreme Value Abbreviations
Abbreviation 
Meaning 

Sub 
Subnormal number 
Num 
Normalized number 
Inf 
Infinity (positive or negative) 
NaN 
Not a Number 
Uno 
Unordered 
Table C4 Extreme Values: Addition and Subtraction
Left Operand 

Right Operand 


0 
Sub 
Num 
Inf 
NaN 

0 

0 
Sub 
Num 
Inf 
NaN 
Sub 

Sub 
Sub 
Num 
Inf 
NaN 
Num 

Num 
Num 
Num 
Inf 
NaN 
Inf 

Inf 
Inf 
Inf 
Note 
NaN 
NaN 

NaN 
NaN 
NaN 
NaN 
NaN 
Note: Inf Inf and Inf + Inf = Inf ; Inf  Inf = NaN.
Table C5 Extreme Values: Multiplication
Left Operand 

Right Operand 


0 
Sub 
Num 
Inf 
NaN 

0 

0 
0 
0 
NaN 
NaN 
Sub 

0 
0 
NS 
Inf 
NaN 
Num 

0 
NS 
Num 
Inf 
NaN 
Inf 

NaN 
Inf 
Inf 
Inf 
NaN 
NaN 

NaN 
NaN 
NaN 
NaN 
NaN 
In the above table, NS means either Num or Sub result possible.
Table C6 Extreme Values: Division
Left Operand 

Right Operand 


0 
Sub 
Num 
Inf 
NaN 

0 

NaN 
0 
0 
0 
NaN 
Sub 

Inf 
Num 
Num 
0 
NaN 
Num 

Inf 
Num 
Num 
0 
NaN 
Inf 

Inf 
Inf 
Inf 
NaN 
NaN 
NaN 

NaN 
NaN 
NaN 
NaN 
NaN 
Table C7 Extreme Values: Comparison
Left Operand 

Right Operand 


0 
Sub 
Num 
Inf 
NaN 

0 

= 
< 
< 
< 
Uno 
Sub 

> 

< 
< 
Uno 
Num 

> 
> 

< 
Uno 
Inf 

> 
> 
> 
= 
Uno 
NaN 

Uno 
Uno 
Uno 
Uno 
Uno 
Notes:
If either X or Y is NaN, then X.NE.Y is .TRUE., and the others (.EQ., .GT., .GE., .LT., .LE.) are .FALSE.
+0 compares equal to 0.
If any argument is NaN, then the results of MAX or MIN are undefined.