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rename NonLinear to NonLinearOptimization
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175
unsupported/Eigen/src/NonLinearOptimization/r1updt.h
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175
unsupported/Eigen/src/NonLinearOptimization/r1updt.h
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template <typename Scalar>
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void ei_r1updt(int m, int n, Scalar *s, int /* ls */, const Scalar *u, Scalar *v, Scalar *w, bool *sing)
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{
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/* Local variables */
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int i, j, l, jj, nm1;
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Scalar tan__;
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int nmj;
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Scalar cos__, sin__, tau, temp, cotan;
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/* Parameter adjustments */
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--w;
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--u;
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--v;
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--s;
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/* Function Body */
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const Scalar giant = std::numeric_limits<Scalar>::max();
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/* initialize the diagonal element pointer. */
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jj = n * ((m << 1) - n + 1) / 2 - (m - n);
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/* move the nontrivial part of the last column of s into w. */
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l = jj;
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for (i = n; i <= m; ++i) {
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w[i] = s[l];
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++l;
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/* L10: */
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}
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/* rotate the vector v into a multiple of the n-th unit vector */
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/* in such a way that a spike is introduced into w. */
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nm1 = n - 1;
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if (nm1 < 1) {
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goto L70;
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}
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for (nmj = 1; nmj <= nm1; ++nmj) {
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j = n - nmj;
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jj -= m - j + 1;
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w[j] = 0.;
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if (v[j] == 0.) {
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goto L50;
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}
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/* determine a givens rotation which eliminates the */
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/* j-th element of v. */
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if (ei_abs(v[n]) >= ei_abs(v[j]))
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goto L20;
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cotan = v[n] / v[j];
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/* Computing 2nd power */
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sin__ = Scalar(.5) / ei_sqrt(Scalar(0.25) + Scalar(0.25) * ei_abs2(cotan));
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cos__ = sin__ * cotan;
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tau = 1.;
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if (ei_abs(cos__) * giant > 1.) {
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tau = 1. / cos__;
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}
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goto L30;
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L20:
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tan__ = v[j] / v[n];
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/* Computing 2nd power */
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cos__ = Scalar(.5) / ei_sqrt(Scalar(0.25) + Scalar(0.25) * ei_abs2(tan__));
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sin__ = cos__ * tan__;
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tau = sin__;
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L30:
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/* apply the transformation to v and store the information */
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/* necessary to recover the givens rotation. */
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v[n] = sin__ * v[j] + cos__ * v[n];
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v[j] = tau;
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/* apply the transformation to s and extend the spike in w. */
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l = jj;
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for (i = j; i <= m; ++i) {
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temp = cos__ * s[l] - sin__ * w[i];
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w[i] = sin__ * s[l] + cos__ * w[i];
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s[l] = temp;
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++l;
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/* L40: */
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}
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L50:
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/* L60: */
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;
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}
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L70:
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/* add the spike from the rank 1 update to w. */
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for (i = 1; i <= m; ++i) {
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w[i] += v[n] * u[i];
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/* L80: */
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}
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/* eliminate the spike. */
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*sing = false;
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if (nm1 < 1) {
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goto L140;
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}
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for (j = 1; j <= nm1; ++j) {
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if (w[j] == 0.) {
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goto L120;
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}
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/* determine a givens rotation which eliminates the */
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/* j-th element of the spike. */
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if (ei_abs(s[jj]) >= ei_abs(w[j]))
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goto L90;
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cotan = s[jj] / w[j];
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/* Computing 2nd power */
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sin__ = Scalar(.5) / ei_sqrt(Scalar(0.25) + Scalar(0.25) * ei_abs2(cotan));
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cos__ = sin__ * cotan;
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tau = 1.;
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if (ei_abs(cos__) * giant > 1.) {
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tau = 1. / cos__;
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}
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goto L100;
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L90:
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tan__ = w[j] / s[jj];
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/* Computing 2nd power */
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cos__ = Scalar(.5) / ei_sqrt(Scalar(0.25) + Scalar(0.25) * ei_abs2(tan__));
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sin__ = cos__ * tan__;
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tau = sin__;
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L100:
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/* apply the transformation to s and reduce the spike in w. */
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l = jj;
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for (i = j; i <= m; ++i) {
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temp = cos__ * s[l] + sin__ * w[i];
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w[i] = -sin__ * s[l] + cos__ * w[i];
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s[l] = temp;
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++l;
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/* L110: */
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}
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/* store the information necessary to recover the */
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/* givens rotation. */
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w[j] = tau;
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L120:
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/* test for zero diagonal elements in the output s. */
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if (s[jj] == 0.) {
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*sing = true;
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}
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jj += m - j + 1;
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/* L130: */
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}
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L140:
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/* move w back into the last column of the output s. */
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l = jj;
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for (i = n; i <= m; ++i) {
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s[l] = w[i];
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++l;
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/* L150: */
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}
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if (s[jj] == 0.) {
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*sing = true;
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}
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return;
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/* last card of subroutine r1updt. */
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} /* r1updt_ */
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