Exponentiation of a complex number is performed by two routines: CTOR, for complex numbers to a real power, and CTOD, for complex numbers to a double-precision power. The only difference between the double-precision power and the real power is that computations are performed by the use of the double-precision functions. Because the final result must be a complex number and no double-precision complex type is supported by any computers, exponentiation to a double-precision power might result in little increased accuracy at a high cost in time, depending on the particular case.