powc16.c

来自「开放源码的编译器open watcom 1.6.0版的源代码」· C语言 代码 · 共 75 行

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#include "variety.h"
#include "cplx.h"
#include "mathcode.h"


_WMRTLINK dcomplex _IF_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( 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 );
    }
}