This function calculates the hyperbolic cosine of specified complex number.
IMCOSH(complex_num)
The complex_num argument is a complex number to return the hyperbolic cosine for.
An error is returned if the complex_num argument is not in the form "x+yi" or "x+yj".
Accepts numeric and string data. Returns string data.
IMCOSH("8-3i") gives the result -1475.563
IMCOSH("7-2i") gives the result -228.180