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C/C++ Source or Header  |  1979-01-10  |  376 b   |  23 lines
  1. #include "complex"
  2.  
  3. c_sqrt(r, z)
  4. complex *r, *z;
  5. {
  6. double mag, sqrt(), cabs();
  7.  
  8. if( (mag = cabs(z->real, z->imag)) == 0.)
  9.     r->real = r->imag = 0.;
  10. else if(z->real > 0)
  11.     {
  12.     r->real = sqrt(0.5 * (mag + z->real) );
  13.     r->imag = z->imag / r->real / 2;
  14.     }
  15. else
  16.     {
  17.     r->imag = sqrt(0.5 * (mag - z->real) );
  18.     if(z->imag < 0)
  19.         r->imag = - r->imag;
  20.     r->real = z->imag / r->imag /2;
  21.     }
  22. }
  23.