void ConvertElevationRotationDegToXYZAngleRad(
    const sal_Int16 nElevationDeg,
    const sal_uInt16 nRotationDeg,
    double& rfXAngleRad, double& rfYAngleRad, double& rfZAngleRad)
{
// issue 72994, description of algorithm see there

// The function expects -90<=nElevationDeg<=90 and 0<=nRotationDeg<=360
// The function delivers -F_PI<=rfXAngleRad<=F_PI, -F_PI<=frZAngleRad<=F_PI and
// -F_PI/2<=rfZAngleRad<=F_PI/2

    double fElevationRad = F_PI*nElevationDeg/180; //elev in description
    double fRotationRad = F_PI*nRotationDeg/180; //azi in description
    double ftanRotationMultSinElevation = 0.0; //initial value is dummy
    double fCosYAngle = 0.0; // initial value is dummy

    if (nRotationDeg == 90 || nRotationDeg == 270)
    {
        //case tan(fRotationRad) not defined
        rfZAngleRad = F_PI/2;
        rfXAngleRad = F_PI - fRotationRad;
        rfYAngleRad = rfXAngleRad - fElevationRad;
    }
    else
    {
        // Do I need ::rtl::math::?
        ftanRotationMultSinElevation = ::rtl::math::tan(fRotationRad) * ::rtl::math::sin(fElevationRad);
        rfZAngleRad = atan(ftanRotationMultSinElevation);
        fCosYAngle = ::rtl::math::cos(fRotationRad)/::rtl::math::cos(rfZAngleRad);
        // Should be in [-1.0; 1.0]. Might it be outside because of rounding
        // errors? Set default values, for security reason.
        if (fCosYAngle < -1.0)
        { 
           fCosYAngle = -1.0;
        } 
        else if (fCosYAngle > 1.0)
            { 
                fCosYAngle = 1.0;
            };
        
        rfYAngleRad = (nRotationDeg<=180)? acos(fCosYAngle) : -acos(fCosYAngle);
        if (::rtl::math::sin(rfYAngleRad)!=0.0)
        {
            rfXAngleRad = atan( ftanRotationMultSinElevation/::rtl::math::sin(rfYAngleRad));
        }
        else // several special cases, see description in issue 72994
        {
            if ((nRotationDeg == 0) || (nRotationDeg == 360))
            {
                rfXAngleRad=fElevationRad; //rfYAngleRad=0.0 and rfZAngleRad=0.0 done above
            }
            else
            {
                if (nRotationDeg==180)
                {
                    rfXAngleRad=-fElevationRad; //rfYAngleRad=F_PI and rfZAngleRad=0.0 done above
                }
                else
                {
                    if ((nElevationDeg==90) || (nElevationDeg==-90))
                    {
                        if ((0<=nRotationDeg) && (nRotationDeg<=90))
                        {
                            rfXAngleRad = fElevationRad;
                            rfYAngleRad = 0.0;
                            rfZAngleRad = (nElevationDeg==90)? fRotationRad : -fRotationRad;
                        }
                        else if ((90<nRotationDeg) && (nRotationDeg<=270))
                        {
                            rfXAngleRad = -fElevationRad;
                            rfYAngleRad = F_PI;
                            rfZAngleRad = (nElevationDeg==90)? fRotationRad-F_PI : F_PI-fRotationRad;
                        }
                        else //270<nRotationDeg<=360
                        {
                            rfXAngleRad = fElevationRad;
                            rfYAngleRad = 0.0;
                            rfZAngleRad = (nElevationDeg==90) ? fRotationRad-F_PI*2 : F_PI*2 -fRotationRad;
                        };
                    }
                    else
                    {
                    // There should not be any other case with sin(rfYAngleRad)==0.0
                    // Please insert debug comment.
                    };
                }  
            }
        } // end of else several special cases
    }
}