Name

Numerical Definitions — mathematical constants, and floating point decomposition.

Library

glib.lib

Synopsis

#include <glib.h>


#define     G_IEEE754_FLOAT_BIAS
#define     G_IEEE754_DOUBLE_BIAS
union       GFloatIEEE754;
union       GDoubleIEEE754;


#define     G_E
#define     G_LN2
#define     G_LN10
#define     G_PI
#define     G_PI_2
#define     G_PI_4
#define     G_SQRT2
#define     G_LOG_2_BASE_10

Detailed Description

GLib offers mathematical constants such as G_PI for the value of pi; many platforms have these in the C library, but some don't, the GLib versions always exist.

The GFloatIEEE754 and GDoubleIEEE754 unions are used to access the sign, mantissa and exponent of IEEE floats and doubles. These unions are defined as appropriate for a given platform. IEEE floats and doubles are supported (used for storage) by at least Intel, PPC and Sparc (for reference, see for example: http://en.wikipedia.org/wiki/IEEE_floating-point_standard

Details

#define G_IEEE754_FLOAT_BIAS	(127)

#define G_IEEE754_DOUBLE_BIAS	(1023)

union GFloatIEEE754
{
  gfloat v_float;
  struct {
    guint mantissa : 23;
    guint biased_exponent : 8;
    guint sign : 1;
  } mpn;
};

union GDoubleIEEE754
{
  gdouble v_double;
  struct {
    guint mantissa_low : 32;
    guint mantissa_high : 20;
    guint biased_exponent : 11;
    guint sign : 1;
  } mpn;
};

#define G_E     2.7182818284590452353602874713526624977572470937000

#define G_LN2   0.69314718055994530941723212145817656807550013436026

#define G_LN10  2.3025850929940456840179914546843642076011014886288

#define G_PI    3.1415926535897932384626433832795028841971693993751

#define G_PI_2  1.5707963267948966192313216916397514420985846996876

#define G_PI_4  0.78539816339744830961566084581987572104929234984378

#define G_SQRT2 1.4142135623730950488016887242096980785696718753769

#define G_LOG_2_BASE_10		(0.30102999566398119521)

See Also

http://en.wikipedia.org/wiki/IEEE_floating-point_standard

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