_WMRTLINK dcomplex _IF_CDLOG( double rp, double ip ) {
//===================================================
// Return the logarithm (base e) of arg.
// ln(x + iy) = u + iv => x + iy = exp(u) * cis(v)
// Thus x*x + y*y = exp(2u) or u = 0.5 ln(x*x + y*y)
// Also y/x = tan(v) so v = atan2(y,x)
dcomplex result;
result.realpart = 0.5 * DLOG( rp*rp + ip*ip );
result.imagpart = DATAN2( ip, rp );
return( result );
}
dcomplex C16Pow( double a, double b, double c, double d ) {
//=========================================================
// Return the real part of the result of taking one double precision
// complex number to the power of another.
// ( a, b ) ** ( c, d ) = exp( ( c,d ) * log( a,b ) )
double u;
double v;
dcomplex arg1;
dcomplex arg2;
dcomplex res;
if( ( a == 0 ) && ( b == 0 ) ) {
if( d == 0 ) {
if( c > 0 ) {
res.realpart = 0;
res.imagpart = 0;
return( res );
}
}
arg1.realpart = a;
arg1.imagpart = b;
arg2.realpart = c;
arg2.imagpart = d;
return( __qmath2err( FP_FUNC_POW | M_DOMAIN | V_ZERO, &arg1, &arg2 ) );
} else {
u = DLOG( a*a + b*b ) / 2;
v = DATAN2( b, a );
res.realpart = DEXP( u*c - v*d );
res.imagpart = res.realpart;
u = u*d + v*c;
res.realpart *= DCOS( u );
res.imagpart *= DSIN( u );
return( res );
}
}
