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

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

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