Limits for floating-point numbers

ARM Compiler toolchain v4.1 for µVision Compiler Reference

This section describes the characteristics of floating-point numbers.

Table 40 gives the characteristics, ranges, and limits for floating-point numbers. These constants are defined in the float.h include file.

Table 40. Floating-point limits

Constant	Meaning	Value
`FLT_MAX`	Maximum value of float	3.40282347e+38F
`FLT_MIN`	Minimum normalized positive floating-point number value of float	1.175494351e-38F
`DBL_MAX`	Maximum value of double	1.79769313486231571e+308
`DBL_MIN`	Minimum normalized positive floating-point number value of double	2.22507385850720138e-308
`LDBL_MAX`	Maximum value of long double	1.79769313486231571e+308
`LDBL_MIN`	Minimum normalized positive floating-point number value of long double	2.22507385850720138e-308
`FLT_MAX_EXP`	Maximum value of base 2 exponent for type float	128
`FLT_MIN_EXP`	Minimum value of base 2 exponent for type float	-125
`DBL_MAX_EXP`	Maximum value of base 2 exponent for type double	1 024
`DBL_MIN_EXP`	Minimum value of base 2 exponent for type double	-1 021
`LDBL_MAX_EXP`	Maximum value of base 2 exponent for type long double	1 024
`LDBL_MIN_EXP`	Minimum value of base 2 exponent for type long double	-1 021
`FLT_MAX_10_EXP`	Maximum value of base 10 exponent for type float	38
`FLT_MIN_10_EXP`	Minimum value of base 10 exponent for type float	-37
`DBL_MAX_10_EXP`	Maximum value of base 10 exponent for type double	308
`DBL_MIN_10_EXP`	Minimum value of base 10 exponent for type double	-307
`LDBL_MAX_10_EXP`	Maximum value of base 10 exponent for type long double	308
`LDBL_MIN_10_EXP`	Minimum value of base 10 exponent for type long double	-307

Table 41 describes other characteristics of floating-point numbers. These constants are also defined in the float.h include file.

Table 41. Other floating-point characteristics

Constant	Meaning	Value
`FLT_RADIX`	Base (radix) of the ARM floating-point number representation	2
`FLT_ROUNDS`	Rounding mode for floating-point numbers	(nearest) 1
`FLT_DIG`	Decimal digits of precision for float	6
`DBL_DIG`	Decimal digits of precision for double	15
`LDBL_DIG`	Decimal digits of precision for long double	15
`FLT_MANT_DIG`	Binary digits of precision for type float	24
`DBL_MANT_DIG`	Binary digits of precision for type double	53
`LDBL_MANT_DIG`	Binary digits of precision for type long double	53
`FLT_EPSILON`	Smallest positive value of x that 1.0 + x != 1.0 for type float	1.19209290e-7F
`DBL_EPSILON`	Smallest positive value of x that 1.0 + x != 1.0 for type double	2.2204460492503131e-16
`LDBL_EPSILON`	Smallest positive value of x that 1.0 + x != 1.0 for type long double	2.2204460492503131e-16L

When a floating-point number is converted to a shorter floating-point number, it is rounded to the nearest representable number.
Floating-point arithmetic conforms to IEEE 754.

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