For a given target accuracy ε, the degrees of the Gauss-Legendre quadrature and spherical t-design (together called the GLST cubature) must be chosen such that Eq. 12 holds. The spherical t-design is similar in its purpose to the Gaussian quadrature where the integral of a function on a unit sphere is converted to a finite sum evaluated at {t m } for which there are M t vectors. The t-design degree refers to the degree of polynomial up to which the spherical t-design exactly represents the spherical integral . Taking into account the symmetry of the GLST cubature, the total number of cubature nodes to use is