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