powic32.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 91 行

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*                            Open Watcom Project
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#include "variety.h"
#include "cplx.h"
#include "mathcode.h"

_WMRTLINK xcomplex _IF_C32PowI( extended a, extended b, intstar4 i )
//==================================================================
{
// Complex power to an integer exponent.

    dcomplex tmp = _IF_C16PowI(a, b, i);
    xcomplex res;
    res.realpart = tmp.realpart;
    res.imagpart = tmp.imagpart;
    return( res );

#ifdef blah // Get rid of this when 10-byte support is enabled
    extended    t;
    xcomplex    arg1;
    xcomplex    arg2;
    xcomplex    res;

    if( ( a == 0 ) && ( b == 0 ) ) {
        if( i > 0 ) {
            res.realpart = 0;
            res.imagpart = 0;
            return( res );
        }
        arg1.realpart = a;
        arg1.imagpart = b;
        arg2.realpart = i;
        arg2.imagpart = 0;
        return( __xmath2err( FUNC_POW | M_DOMAIN | V_ZERO, &arg1, &arg2 ) );
    } else {
        if( i < 0 ) {
            i = -i;
            t = a*a + b*b;
            a = a / t;
            b = -b / t;
        }
        res.realpart = 1;
        res.imagpart = 0;
        while( i > 0 ) {
            if( i % 2 == 0 ) {
                t = a;
                a = a*a - b*b;
                b = 2*t*b;
                i = i / 2;
            } else {
                t = res.realpart;
                res.realpart = res.realpart*a - res.imagpart*b;
                res.imagpart = t*b + res.imagpart*a;
                --i;
            }
        }
        return res;
    }
#endif
}