mat3x3:
        mat[0]= cos(y)cos(z) = 1/2 (cos(y-z)+cos(y+z))
        mat[1]= -cos(y)sin(z) = 1/2 (sin(y-z)-sin(y+z))
        mat[2]= sin(y)

        mat[3]= sin(x)sin(y)cos(z)+cos(x)sin(z)
=1/4 (cos(x-y-z)-cos(x+y-z)+cos(x-y+z)-cos(x+y+z)-2 sin(x-z)+2 sin(x+z))

        mat[4]=cos(x)cos(z)-sin(x)sin(y)sin(z)
=1/4 (2 cos(x+z)+2cos(x+z) -sin(x+y+z)-sin(x+y-z)+sin(x-y+z)-sin(x-y-z))

        mat[5]= -sin(x)cos(y) = 1/2 (-sin(x-y)-sin(x+y))

        mat[6]=sin(x)sin(z)-cos(x)cos(z)sin(y)
=1/4 (2 cos(x-z)-2cos(x+z) -sin(x+y+z)-sin(x-y+z)+sin(x+y-z)-sin(x-y-z))

        mat[7]=cos(z)sin(x)+cos(x)sin(y)sin(z)
=1/4 (2sin(x+z)+2sin(x-z) + cos(x-y-z)-cos(x+y-z)+cos(x-y+z)-cos(x+y+z)
        mat[8]=cos(x)cos(y) = 1/2 (cos(x-y)+cos(x+y))