39 lines
568 B
C
39 lines
568 B
C
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#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(resx, z) complex *resx, *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 *resx, complex *z)
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#endif
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{
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double mag, t;
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complex res;
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if( (mag = f__cabs(z->r, z->i)) == 0.)
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res.r = res.i = 0.;
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else if(z->r > 0)
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{
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res.r = t = sqrt(0.5 * (mag + z->r) );
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t = z->i / t;
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res.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 - z->r) );
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if(z->i < 0)
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t = -t;
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res.i = t;
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t = z->i / t;
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res.r = 0.5 * t;
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}
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resx->r = res.r;
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resx->i = res.i;
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}
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