_WMRTLINK double _IF_dlog( double x )
/***********************************/
{
int exp;
double z;
if( x <= 0.0 ) {
x = __log87_err( x, FP_FUNC_LOG );
#if defined(_M_IX86)
} else if( _RWD_real87 ) {
x = _log87( x );
#endif
} else {
x = frexp( x, &exp );
z = x - .5;
if( x > sqrt_of_half ) {
z -= .5;
} else {
x = z;
--exp;
}
z = z / (x * .5 + .5);
x = z * z;
x = z + z * x * _EvalPoly( x, APoly, 2 ) / _EvalPoly( x, BPoly, 3 );
if( exp != 0 ) {
z = exp;
x = (z * C2 + x) + z * C1;
}
}
return( x );
}
_WMRTLINK double y1( double x ) /* Bessel function y1(x) */
/*******************/
{
double xx, y, z;
if( x < 0.0 ) {
// z = _matherr( DOMAIN, "y1", &x, &x, - HUGE_VAL );
z = __math1err( FUNC_Y1 | M_DOMAIN | V_NEG_HUGEVAL, &x );
} else if( x < 8.0 ) {
y = x * x;
z = PDIV( x * _EvalPoly( y, _Y1P, 10 ) , _EvalPoly( y, _Y1Q, 4 ) )
+ Two_over_pi * ( j1(x) * log(x) - PDIV(1.0,x) );
} else {
z = PDIV( 8.0 , x );
y = z * z;
xx = x - ThreePIby4;
z = sqrt( PDIV( Two_over_pi , x ) ) *
( PDIV( sin(xx) * _EvalPoly( y, _P1P, 4 ) , _EvalPoly( y, _P1Q, 5 ) )
+ z * cos(xx) *(PDIV(_EvalPoly( y, _Q1P, 4 ) , _EvalPoly( y, _Q1Q, 4 ))));
}
return( z );
}
_WMRTLINK double j1( double x ) /* Bessel function j1(x) */
/*****************************/
{
double ax, xx, y, z;
ax = fabs( x );
if( ax < 8.0 ) {
y = x * x;
z = PDIV( x * _EvalPoly( y, _J1P, 7 ) , _EvalPoly( y, _J1Q, 7 ) );
} else {
z = PDIV( 8.0, ax );
y = z * z;
xx = ax - ThreePIby4;
z = sqrt( PDIV( TwobyPI, ax ) ) *
( PDIV( cos( xx ) * _EvalPoly( y, _P1P, 4 ) , _EvalPoly( y, _P1Q, 5 ) )
- z * sin( xx ) * (PDIV( _EvalPoly( y, _Q1P, 4 ) , _EvalPoly( y, _Q1Q, 4 ) )) );
if( x < 0.0 ) {
z = - z;
}
}
return( z );
}
