...
Gnu Mpc is a C library for the arithmetic ofcomplex of complex numbers with arbitrarily high precision and correctrounding correct rounding of the result. It extends the principles of the IEEE-754standard 754 standard for fixed precision real floating point numbers tocomplex to complex numbers, providing well-defined semantics for everyoperationevery operation. At the same time, speed of operation at high precisionis precision is a major design goal.
More information
...