The SetRotationAboutY function sets the given matrix to a rotation about the y-axis, using the specified number of radians. This function is called as part of the AnimateScene function, documented in Animating the Scene.
static void
SetRotationAboutY(LPD3DMATRIX lpd3dMatrix, double dAngleOfRotation)
{
D3DVALUE dvCos;
D3DVALUE dvSin;
ASSERT(NULL != lpd3dMatrix);
dvCos = D3DVAL(cos(dAngleOfRotation));
dvSin = D3DVAL(sin(dAngleOfRotation));
lpd3dMatrix->_11 = dvCos;
lpd3dMatrix->_12 = D3DVAL(0.0);
lpd3dMatrix->_13 = -dvSin;
lpd3dMatrix->_14 = D3DVAL(0.0);
lpd3dMatrix->_21 = D3DVAL(0.0);
lpd3dMatrix->_22 = D3DVAL(1.0);
lpd3dMatrix->_23 = D3DVAL(0.0);
lpd3dMatrix->_24 = D3DVAL(0.0);
lpd3dMatrix->_31 = dvSin;
lpd3dMatrix->_32 = D3DVAL(0.0);
lpd3dMatrix->_33 = dvCos;
lpd3dMatrix->_34 = D3DVAL(0.0);
lpd3dMatrix->_41 = D3DVAL(0.0);
lpd3dMatrix->_42 = D3DVAL(0.0);
lpd3dMatrix->_43 = D3DVAL(0.0);
lpd3dMatrix->_44 = D3DVAL(1.0);
}