59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
#ifdef __cplusplus
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extern "C" {
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#endif
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#include "lmp_f2c.h"
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int dlaed5_(integer *i__, doublereal *d__, doublereal *z__, doublereal *delta, doublereal *rho,
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doublereal *dlam)
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{
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doublereal d__1;
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double sqrt(doublereal);
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doublereal b, c__, w, del, tau, temp;
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--delta;
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--z__;
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--d__;
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del = d__[2] - d__[1];
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if (*i__ == 1) {
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w = *rho * 2. * (z__[2] * z__[2] - z__[1] * z__[1]) / del + 1.;
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if (w > 0.) {
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b = del + *rho * (z__[1] * z__[1] + z__[2] * z__[2]);
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c__ = *rho * z__[1] * z__[1] * del;
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tau = c__ * 2. / (b + sqrt((d__1 = b * b - c__ * 4., abs(d__1))));
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*dlam = d__[1] + tau;
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delta[1] = -z__[1] / tau;
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delta[2] = z__[2] / (del - tau);
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} else {
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b = -del + *rho * (z__[1] * z__[1] + z__[2] * z__[2]);
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c__ = *rho * z__[2] * z__[2] * del;
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if (b > 0.) {
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tau = c__ * -2. / (b + sqrt(b * b + c__ * 4.));
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} else {
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tau = (b - sqrt(b * b + c__ * 4.)) / 2.;
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}
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*dlam = d__[2] + tau;
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delta[1] = -z__[1] / (del + tau);
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delta[2] = -z__[2] / tau;
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}
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temp = sqrt(delta[1] * delta[1] + delta[2] * delta[2]);
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delta[1] /= temp;
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delta[2] /= temp;
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} else {
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b = -del + *rho * (z__[1] * z__[1] + z__[2] * z__[2]);
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c__ = *rho * z__[2] * z__[2] * del;
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if (b > 0.) {
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tau = (b + sqrt(b * b + c__ * 4.)) / 2.;
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} else {
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tau = c__ * 2. / (-b + sqrt(b * b + c__ * 4.));
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}
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*dlam = d__[2] + tau;
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delta[1] = -z__[1] / (del + tau);
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delta[2] = -z__[2] / tau;
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temp = sqrt(delta[1] * delta[1] + delta[2] * delta[2]);
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delta[1] /= temp;
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delta[2] /= temp;
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}
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return 0;
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}
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#ifdef __cplusplus
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}
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#endif
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