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c_sqrt.c
Go to the documentation of this file.00001 #include "f2c.h"
00002
00003 #ifdef KR_headers
00004 extern double sqrt(), f__cabs();
00005
00006 VOID c_sqrt(r, z) complex *r, *z;
00007 #else
00008 #undef abs
00009 #include "mathh.h"
00010 extern double f__cabs(double, double);
00011
00012 void c_sqrt(complex *r, complex *z)
00013 #endif
00014 {
00015 double mag, t;
00016
00017 if( (mag = f__cabs(z->r, z->i)) == 0.)
00018 r->r = r->i = 0.;
00019 else if(z->r > 0)
00020 {
00021 r->r = t = sqrt(0.5 * (mag + z->r) );
00022 t = z->i / t;
00023 r->i = 0.5 * t;
00024 }
00025 else
00026 {
00027 t = sqrt(0.5 * (mag - z->r) );
00028 if(z->i < 0)
00029 t = -t;
00030 r->i = t;
00031 t = z->i / t;
00032 r->r = 0.5 * t;
00033 }
00034 }
