#ifdef __cplusplus
extern "C" {
#endif
#include "lmp_f2c.h"
doublereal dnrm2_(integer *n, doublereal *x, integer *incx)
{
    integer i__1, i__2;
    doublereal ret_val, d__1;
    double sqrt(doublereal);
    integer ix;
    doublereal ssq, norm, scale, absxi;
    --x;
    if (*n < 1 || *incx < 1) {
        norm = 0.;
    } else if (*n == 1) {
        norm = abs(x[1]);
    } else {
        scale = 0.;
        ssq = 1.;
        i__1 = (*n - 1) * *incx + 1;
        i__2 = *incx;
        for (ix = 1; i__2 < 0 ? ix >= i__1 : ix <= i__1; ix += i__2) {
            if (x[ix] != 0.) {
                absxi = (d__1 = x[ix], abs(d__1));
                if (scale < absxi) {
                    d__1 = scale / absxi;
                    ssq = ssq * (d__1 * d__1) + 1.;
                    scale = absxi;
                } else {
                    d__1 = absxi / scale;
                    ssq += d__1 * d__1;
                }
            }
        }
        norm = scale * sqrt(ssq);
    }
    ret_val = norm;
    return ret_val;
}
#ifdef __cplusplus
}
#endif