“…However, for practical purposes, the following modified functions are more convenient than the functions above: tam p,q x := sin p,q x cos p/q p,q x , tamh p,q x := sinh p,q x cosh p/q p,q x . These modified functions were first introduced in [8,12] with the symbols τ p,q , τp,q , respectively. Note that if p = q, then tam p,q x = tan p,q x and tamh p,q x = tanh p,q x.…”