ifcqcos.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 62 行

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//
// IFCQCOS      : cosine function for COMPLEX*20 argument
//

#include "fmath.h"

#include "ftnstd.h"
#include "ifenv.h"

xcomplex        CQCOS( extended rp, extended ip ) {
//=============================================

// Return the cosine of arg.
// cos( x + iy ) = ( exp( ix ) exp( -y ) + exp( -ix ) exp( y ) ) / 2
//               = ( cis( x ) exp( -y ) + cis( -x ) exp( y ) ) / 2
//               = cos( x ) cosh( y ) - i sin( x ) sinh( y )

    xcomplex    result;

    result.realpart = cos( rp ) * cosh( ip );
    result.imagpart = -sin( rp ) * sinh( ip );
    return( result );
}

xcomplex XCQCOS( xcomplex *arg ) {
//================================

    return( CQCOS( arg->realpart, arg->imagpart ) );
}