Sech​(AngouriMath.​Entity)

Console.WriteLine(Sech("x"));
Console.WriteLine(Sech("x").Substitute("x", 1.5).Evaled);
Console.WriteLine(Sech("x").Substitute("x", 0.01).Evaled);
Console.WriteLine("-----------------------------");
Console.WriteLine(Cosech("x"));
Console.WriteLine(Cosech("x").Substitute("x", 1.5).Evaled);
Console.WriteLine(Cosech("x").Substitute("x", 0.01).Evaled);

1 / ((e ^ x + e ^ (-x)) / 2)
0.42509
0.99995
-----------------------------
1 / ((e ^ x - e ^ (-x)) / 2)
0.46964
99.9983