Function calcu_rs::algos::expand_sin_n_times_phi

fn expand_sin_n_times_phi(n: i128, phi: &Expr) -> Expr

expands the expression sin(n*phi) to

sin(n*phi) = sum(j=1 && odd(j); n) { (-1)^((j-1)/2) * binom(n,j) * cos(phi)^(n-j) * sin(phi)^j }