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Annotation of researchv10no/libF77/c_sqrt.c, revision 1.1

1.1     ! root        1: #include "f2c.h"
        !             2: 
        !             3: #ifdef KR_headers
        !             4: extern double sqrt(), f__cabs();
        !             5: 
        !             6: VOID c_sqrt(r, z) complex *r, *z;
        !             7: #else
        !             8: #undef abs
        !             9: #include "math.h"
        !            10: extern double f__cabs(double, double);
        !            11: 
        !            12: void c_sqrt(complex *r, complex *z)
        !            13: #endif
        !            14: {
        !            15: double mag, t;
        !            16: 
        !            17: if( (mag = f__cabs(z->r, z->i)) == 0.)
        !            18:        r->r = r->i = 0.;
        !            19: else if(z->r > 0)
        !            20:        {
        !            21:        r->r = t = sqrt(0.5 * (mag + z->r) );
        !            22:        t = z->i / t;
        !            23:        r->i = 0.5 * t;
        !            24:        }
        !            25: else
        !            26:        {
        !            27:        t = sqrt(0.5 * (mag - z->r) );
        !            28:        if(z->i < 0)
        !            29:                t = -t;
        !            30:        r->i = t;
        !            31:        t = z->i / t;
        !            32:        r->r = 0.5 * t;
        !            33:        }
        !            34: }

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