cpow, cpowf,
  cpowl —
complex power functions
#include <complex.h>
double complex
  
  cpow(double
    complex x, double complex
    y);
float complex
  
  cpowf(float
    complex x, float complex
    y);
long double complex
  
  cpowl(long
    double complex x, long
    double complex y);
These functions compute the complex power function x**y, with a branch cut for
  the first parameter along the negative real axis.
These functions return the complex power function value.
Portions of this text are reprinted and reproduced in electronic form from IEEE
  Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
  Operating System Interface (POSIX), The Open Group Base Specifications Issue
  6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
  Engineers, Inc and The Open Group. In the event of any discrepancy between
  this version and the original IEEE and The Open Group Standard, the original
  IEEE and The Open Group Standard is the referee document. The original
  Standard can be obtained online at http://www.opengroup.org/unix/online.html .