36 lines
538 B
C
36 lines
538 B
C
|
#include "f2c.h"
|
||
|
|
|
||
|
|
#ifdef KR_headers
|
||
|
|
extern double sqrt(), f__cabs();
|
||
|
|
|
||
|
|
VOID c_sqrt(r, z) complex *r, *z;
|
||
|
|
#else
|
||
|
|
#undef abs
|
||
|
|
#include "math.h"
|
||
|
|
extern double f__cabs(double, double);
|
||
|
|
|
||
|
|
void c_sqrt(complex *r, complex *z)
|
||
|
|
#endif
|
||
|
|
{
|
||
|
|
double mag, t;
|
||
|
|
double zi = z->i, zr = z->r;
|
||
|
|
|
||
|
|
if( (mag = f__cabs(zr, zi)) == 0.)
|
||
|
|
r->r = r->i = 0.;
|
||
|
|
else if(zr > 0)
|
||
|
|
{
|
||
|
|
r->r = t = sqrt(0.5 * (mag + zr) );
|
||
|
|
t = zi / t;
|
||
|
|
r->i = 0.5 * t;
|
||
|
|
}
|
||
|
|
else
|
||
|
|
{
|
||
|
|
t = sqrt(0.5 * (mag - zr) );
|
||
|
|
if(zi < 0)
|
||
|
|
t = -t;
|
||
|
|
r->i = t;
|
||
|
|
t = zi / t;
|
||
|
|
r->r = 0.5 * t;
|
||
|
|
}
|
||
|
|
}
|