float
__ieee754_gammaf_r (float x, int *signgamp)
{
/* We don't have a real gamma implementation now. We'll use lgamma
and the exp function. But due to the required boundary
conditions we must check some values separately. */
int32_t hx;
GET_FLOAT_WORD (hx, x);
if (__builtin_expect ((hx & 0x7fffffff) == 0, 0))
{
/* Return value for x == 0 is Inf with divide by zero exception. */
*signgamp = 0;
return 1.0 / x;
}
if (__builtin_expect (hx < 0, 0)
&& (u_int32_t) hx < 0xff800000 && __rintf (x) == x)
{
/* Return value for integer x < 0 is NaN with invalid exception. */
*signgamp = 0;
return (x - x) / (x - x);
}
if (__builtin_expect (hx == 0xff800000, 0))
{
/* x == -Inf. According to ISO this is NaN. */
*signgamp = 0;
return x - x;
}
/* XXX FIXME. */
return __ieee754_expf (__ieee754_lgammaf_r (x, signgamp));
}
DLLEXPORT float
__ieee754_lgammaf(float x)
{
#ifdef OPENLIBM_ONLY_THREAD_SAFE
int signgam;
#endif
return __ieee754_lgammaf_r(x,&signgam);
}
float
lgammaf_r(float x, int *signgamp) /* wrapper lgammaf_r */
{
#ifdef _IEEE_LIBM
return __ieee754_lgammaf_r(x,signgamp);
#else
float y;
y = __ieee754_lgammaf_r(x,signgamp);
if(_LIB_VERSION == _IEEE_) return y;
if(!finitef(y)&&finitef(x)) {
if(floorf(x)==x&&x<=(float)0.0)
/* lgamma pole */
return (float)__kernel_standard((double)x,(double)x,115);
else
/* lgamma overflow */
return (float)__kernel_standard((double)x,(double)x,114);
} else
return y;
#endif
}
float
gammaf(float x)
{
#ifdef _IEEE_LIBM
return __ieee754_lgammaf_r(x,&signgam);
#else
float y;
y = __ieee754_lgammaf_r(x,&signgam);
if(_LIB_VERSION == _IEEE_) return y;
if(!finitef(y)&&finitef(x)) {
if(floorf(x)==x&&x<=(float)0.0)
/* gammaf pole */
return (float)__kernel_standard((double)x,(double)x,141);
else
/* gammaf overflow */
return (float)__kernel_standard((double)x,(double)x,140);
} else
return y;
#endif
}
float
__lgammaf_r(float x, int *signgamp)
{
float y = __ieee754_lgammaf_r(x,signgamp);
if(__builtin_expect(!__finitef(y), 0)
&& __finitef(x) && _LIB_VERSION != _IEEE_)
return __kernel_standard_f(x, x,
__floorf(x)==x&&x<=0.0f
? 115 /* lgamma pole */
: 114); /* lgamma overflow */
return y;
}
float
__ieee754_gammaf_r(float x, int *signgamp)
{
return __ieee754_lgammaf_r(x,signgamp);
}
static float
gammaf_positive (float x, int *exp2_adj)
{
int local_signgam;
if (x < 0.5f)
{
*exp2_adj = 0;
return __ieee754_expf (__ieee754_lgammaf_r (x + 1, &local_signgam)) / x;
}
else if (x <= 1.5f)
{
*exp2_adj = 0;
return __ieee754_expf (__ieee754_lgammaf_r (x, &local_signgam));
}
else if (x < 2.5f)
{
*exp2_adj = 0;
float x_adj = x - 1;
return (__ieee754_expf (__ieee754_lgammaf_r (x_adj, &local_signgam))
* x_adj);
}
else
{
float eps = 0;
float x_eps = 0;
float x_adj = x;
float prod = 1;
if (x < 4.0f)
{
/* Adjust into the range for applying Stirling's
approximation. */
float n = __ceilf (4.0f - x);
x_adj = math_narrow_eval (x + n);
x_eps = (x - (x_adj - n));
prod = __gamma_productf (x_adj - n, x_eps, n, &eps);
}
/* The result is now gamma (X_ADJ + X_EPS) / (PROD * (1 + EPS)).
Compute gamma (X_ADJ + X_EPS) using Stirling's approximation,
starting by computing pow (X_ADJ, X_ADJ) with a power of 2
factored out. */
float exp_adj = -eps;
float x_adj_int = __roundf (x_adj);
float x_adj_frac = x_adj - x_adj_int;
int x_adj_log2;
float x_adj_mant = __frexpf (x_adj, &x_adj_log2);
if (x_adj_mant < (float) M_SQRT1_2)
{
x_adj_log2--;
x_adj_mant *= 2.0f;
}
*exp2_adj = x_adj_log2 * (int) x_adj_int;
float ret = (__ieee754_powf (x_adj_mant, x_adj)
* __ieee754_exp2f (x_adj_log2 * x_adj_frac)
* __ieee754_expf (-x_adj)
* __ieee754_sqrtf (2 * (float) M_PI / x_adj)
/ prod);
exp_adj += x_eps * __ieee754_logf (x_adj);
float bsum = gamma_coeff[NCOEFF - 1];
float x_adj2 = x_adj * x_adj;
for (size_t i = 1; i <= NCOEFF - 1; i++)
bsum = bsum / x_adj2 + gamma_coeff[NCOEFF - 1 - i];
exp_adj += bsum / x_adj;
return ret + ret * __expm1f (exp_adj);
}
}
float
__ieee754_lgammaf(float x)
{
return __ieee754_lgammaf_r(x,&signgam);
}
//------------------------------------------------------------------------------
float Cmath::lgammaf( float x )
{
float y;
struct fexception exc;
y = __ieee754_lgammaf_r( x, &m_isigngam );
if( m_fdlib_version == _IEEE_ )
{
return y;
}
if( !finitef( y ) && finitef( x ) )
{
exc.name = "lgammaf";
exc.err = 0;
exc.arg1 = exc.arg2 = (double)x;
if( m_fdlib_version == _SVID_ )
{
exc.retval = Huge();
}
else
{
exc.retval = HUGE_VAL;
}
if( floorf( x ) == x && x <= (float)0.0 )
{
// lgammaf(-integer)
exc.type = EX_SING;
if( m_fdlib_version == _POSIX_ )
{
errno = EDOM;
}
else if( !matherr( &exc ) )
{
errno = EDOM;
}
}
else
{
// lgammaf(finite) overflow
exc.type = EX_OVERFLOW;
if( m_fdlib_version == _POSIX_ )
{
errno = ERANGE;
}
else if( !matherr( &exc ) )
{
errno = ERANGE;
}
}
if( exc.err != 0 )
{
errno = exc.err;
}
return (float)exc.retval;
}
else
{
return y;
}
}
//------------------------------------------------------------------------------
float Cmath::lgammaf_r( float x, int* signgamp )
{
float y;
struct fexception exc;
y = __ieee754_lgammaf_r( x, signgamp );
if( m_fdlib_version == _IEEE_ )
{
return y;
}
if( !finitef( y ) && finitef( x ) )
{
# ifndef HUGE_VAL
# define HUGE_VAL inf
double inf = 0.0;
set_high_word( inf, 0x7ff00000 ); // set inf to infinite
# endif
exc.name = "lgammaf";
exc.err = 0;
exc.arg1 = exc.arg2 = (double)x;
if( m_fdlib_version == _SVID_ )
{
exc.retval = Huge();
}
else
{
exc.retval = HUGE_VAL;
}
if( floorf( x ) == x && x <= (float)0.0 )
{
// lgammaf(-integer) or lgamma(0)
exc.type = EX_SING;
if( m_fdlib_version == _POSIX_ )
{
errno = EDOM;
}
else if( !matherr( &exc ) )
{
errno = EDOM;
}
}
else
{
// lgammaf(finite) overflow
exc.type = EX_OVERFLOW;
if( m_fdlib_version == _POSIX_ )
{
errno = ERANGE;
}
else if( !matherr( &exc ) )
{
errno = ERANGE;
}
}
if( exc.err != 0 )
{
errno = exc.err;
}
return (float)exc.retval;
}
else
{
return y;
}
}
