Headers float.h(3HEAD)
NAME
float.h, float - floating types
SYNOPSIS
#include
DESCRIPTION
The characteristics of floating types are defined in terms
of a model that describes a representation of floating-point
numbers and values that provide information about animplementation's floating-point arithmetic.
The following parameters are used to define the model foreach floating-point type:
s sign (+_1)
b base or radix of exponent representation (an integer >1) e exponent (an integer between a minimum e(min) and a maximum e(max))p precision (the number of base-b digits in the signifi-
cand)f(k) non-negative integers less than b (the significand
digits)In addition to normalized floating-point numbers (f(1)>0 if
x=/0), floating types might be able to contain other kinds of
floating-point numbers, such as subnormal floating-point
numbers (x=/0, e=e(min), f(1)=0) and unnormalized floating-
point numbers (x=/0, e=e(min), f(1)=0), and values that arenot floating-point numbers, such as infinities and NaNs. A
NaN is an encoding signifying Not-a-Number. A quiet NaN pro-
pagates through almost every arithmetic operation withoutraising a floating-point exception; a signaling NaN gen-
erally raises a floating-point exception when occurring as
an arithmetic operand. The accuracy of the library functions in math.h(3HEAD) andcomplex.h(3HEAD) that return floating-point results is
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Headers float.h(3HEAD)
defined on the libm(3LIB) manual page.All integer values in the
header, except FLT_ROUNDS, are constant expressions suitable for use in #if
preprocessing directives; all floating values are constant
expressions. All except DECIMAL_DIG, FLT_EVAL_METHOD,
FLT_RADIX, and FLT_ROUNDS have separate names for all three
floating-point types. The floating-point model representa-
tion is provided for all values except FLT_EVAL_METHOD and
FLT_ROUNDS.
The rounding mode for floating-point addition is character-
ized by the value of FLT_ROUNDS:
-1 Indeterminable.
0 Toward zero. 1 To nearest. 2 Toward positive infinity. 3 Toward negative infinity.The values of operations with floating operands and values
subject to the usual arithmetic conversions and of floating
constants are evaluated to a format whose range and preci-
sion might be greater than required by the type. The use ofevaluation formats is characterized by the architecture-
dependent value of FLT_EVAL_METHOD:
-1 Indeterminable.
0 Evaluate all operations and constants just to the range and precision of the type.1 Evaluate operations and constants of type float and
double to the range and precision of the double type; evaluate long double operations and constants to the range and precision of the long double type.SunOS 5.11 Last change: 17 Dec 2003 2
Headers float.h(3HEAD)
2 Evaluate all operations and constants to the range and precision of the long double type.The values given in the following list are defined as con-
stants. o Radix of exponent representation, b.FLT_RADIX
o Number of base-FLT_RADIX digits in the floating-
point significand, p.FLT_MANT_DIG
DBL_MANT_DIG
LDBL_MANT_DIG
o Number of decimal digits, n, such that anyfloating-point number in the widest supported
floating type with p(max) radix b digits can be
rounded to a floating-point number with n decimal
digits and back again without change to the value.DECIMAL_DIG
o Number of decimal digits, q, such that anyfloating-point number with q decimal digits can be
rounded into a floating-point number with p radix b
digits and back again without change to the q decimal digits.FLT_DIG
DBL_DIG
LDBL_DIG
o Minimum negative integer such that FLT_RADIX raised
to that power minus 1 is a normalized floating-
point number, e(min).FLT_MIN_EXP
DBL_MIN_EXP
LDBL_MIN_EXP
o Minimum negative integer such that 10 raised tothat power is in the range of normalized floating-
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Headers float.h(3HEAD)
point numbers.FLT_MIN_10_EXP
DBL_MIN_10_EXP
LDBL_MIN_10_EXP
o Maximum integer such that FLT_RADIX raised to that
power minus 1 is a representable finite floating-
point number, e(max).FLT_MAX_EXP
DBL_MAX_EXP
LDBL_MAX_EXP
o Maximum integer such that 10 raised to that poweris in the range of representable finite floating-
point numbers.FLT_MAX_10_EXP
DBL_MAX_10_EXP
LDBL_MAX_10_EXP
The values given in the following list are defined as con-
stant expressions with values that are greater than or equal to those shown:o Maximum representable finite floating-point number.
FLT_MAX
DBL_MAX
LDBL_MAX
The values given in the following list are defined as con-
stant expressions with implementation-defined (positive)
values that are less than or equal to those shown: o The difference between 1 and the least value greater than 1 that is representable in the givenfloating-point type, b^1 - p.
FLT_EPSILON
DBL_EPSILON
LDBL_EPSILON
o Minimum normalized positive floating-point number,
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Headers float.h(3HEAD)
b^e(min)^-1.
FLT_MIN
DBL_MIN
LDBL_MIN
ATTRIBUTES
See attributes(5) for descriptions of the following attri-
butes:____________________________________________________________
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|_____________________________|_____________________________|
| Interface Stability | Committed ||_____________________________|_____________________________|
| Standard | See standards(5). ||_____________________________|_____________________________|
SEE ALSO
complex.h(3HEAD), math.h(3HEAD), attributes(5), standards(5)SunOS 5.11 Last change: 17 Dec 2003 5