FUNCTION tb_zyx, a, b, g
    ;+#tb_zyx
    ;+Calculates Tait-Bryan z-y'-x" active rotation matrix given rotation angles `alpha`,`beta`,`gamma` in radians
    ;+##Arguments
    ;+     **alpha**: rotation angle about z [radians]
    ;+
    ;+     **beta**: rotation angle about y' [radians]
    ;+
    ;+     **gamma**: rotation angle about x" [radians]
    ;+
    ;+##Return Value
    ;+     Rotation Matrix [prefida](|url|/sourcefile/prefida.pro.html)
    ;+
    ;+##Example Usage
    ;+```idl
    ;+ IDL> rot_mat = tb_zyx(!DPI/2, 0.0, !DPI/3)
    ;+```
    sa = sin(a) & ca = cos(a)
    sb = sin(b) & cb = cos(b)
    sg = sin(g) & cg = cos(g)

    R = dblarr(3,3)
    R[0,0] = ca*cb & R[1,0] = ca*sb*sg - cg*sa & R[2,0] = sa*sg + ca*cg*sb
    R[0,1] = cb*sa & R[1,1] = ca*cg + sa*sb*sg & R[2,1] = cg*sa*sb - ca*sg
    R[0,2] = -sb   & R[1,2] = cb*sg            & R[2,2] = cb*cg

    return, R
END