HP-UX Floating-Point Guide

64 Chapter 2
Floating-Point Principles and the IEEE Standard for Binary Floating-Point Arithmetic
Floating-Point Operations
Infinity To the comparison operators, infinity is just another
signed numeric value whose magnitude is greater than
the largest normalized magnitude. Infinities with the
same sign compare as equal to each other.
NaN A NaN compares as unequal to all other operands,
including other NaNs and itself. The rules above are
used to evaluate assertions involving NaNs as TRUE
or FALSE. If the assertion is non-aware, an invalid
operation exception is also signaled for any comparison
involving a <, <=, >, or >= assertion.
Conversion Between Operand Formats
The standard requires that it be possible to convert between decimal and
binary floating-point, and between binary floating-point and integer
formats. This section describes some of the properties of various
conversions. The operand type integer refers to either signed or
unsigned integers.
Single-Precision to
Double-Precision or
Quad-Precision These conversions can never overflow,
underflow, or be inexact. The only
possible type of exception is an
invalid operation if the operand is an
SNaN.
Double-Precision to
Quad-Precision These conversions can never overflow,
underflow, or be inexact. The only
possible type of exception is an
invalid operation if the operand is an
SNaN.
Quad-Precision or
Double-Precision to
Single-Precision These conversions can overflow or
underflow and are usually inexact.
Quad-Precision to
Double-Precision These conversions can overflow or
underflow and are usually inexact.