--- /dev/null
+#include "clapack.h"
+
+/* Table of constant values */
+
+static doublereal c_b9 = 0.;
+static doublereal c_b10 = 1.;
+static integer c__0 = 0;
+static integer c__1 = 1;
+static integer c__2 = 2;
+
+/* Subroutine */ int dsteqr_(char *compz, integer *n, doublereal *d__,
+ doublereal *e, doublereal *z__, integer *ldz, doublereal *work,
+ integer *info)
+{
+ /* System generated locals */
+ integer z_dim1, z_offset, i__1, i__2;
+ doublereal d__1, d__2;
+
+ /* Builtin functions */
+ double sqrt(doublereal), d_sign(doublereal *, doublereal *);
+
+ /* Local variables */
+ doublereal b, c__, f, g;
+ integer i__, j, k, l, m;
+ doublereal p, r__, s;
+ integer l1, ii, mm, lm1, mm1, nm1;
+ doublereal rt1, rt2, eps;
+ integer lsv;
+ doublereal tst, eps2;
+ integer lend, jtot;
+ extern /* Subroutine */ int dlae2_(doublereal *, doublereal *, doublereal
+ *, doublereal *, doublereal *);
+ extern logical lsame_(char *, char *);
+ extern /* Subroutine */ int dlasr_(char *, char *, char *, integer *,
+ integer *, doublereal *, doublereal *, doublereal *, integer *);
+ doublereal anorm;
+ extern /* Subroutine */ int dswap_(integer *, doublereal *, integer *,
+ doublereal *, integer *), dlaev2_(doublereal *, doublereal *,
+ doublereal *, doublereal *, doublereal *, doublereal *,
+ doublereal *);
+ integer lendm1, lendp1;
+ extern doublereal dlapy2_(doublereal *, doublereal *), dlamch_(char *);
+ integer iscale;
+ extern /* Subroutine */ int dlascl_(char *, integer *, integer *,
+ doublereal *, doublereal *, integer *, integer *, doublereal *,
+ integer *, integer *), dlaset_(char *, integer *, integer
+ *, doublereal *, doublereal *, doublereal *, integer *);
+ doublereal safmin;
+ extern /* Subroutine */ int dlartg_(doublereal *, doublereal *,
+ doublereal *, doublereal *, doublereal *);
+ doublereal safmax;
+ extern /* Subroutine */ int xerbla_(char *, integer *);
+ extern doublereal dlanst_(char *, integer *, doublereal *, doublereal *);
+ extern /* Subroutine */ int dlasrt_(char *, integer *, doublereal *,
+ integer *);
+ integer lendsv;
+ doublereal ssfmin;
+ integer nmaxit, icompz;
+ doublereal ssfmax;
+
+
+/* -- LAPACK routine (version 3.1) -- */
+/* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
+/* November 2006 */
+
+/* .. Scalar Arguments .. */
+/* .. */
+/* .. Array Arguments .. */
+/* .. */
+
+/* Purpose */
+/* ======= */
+
+/* DSTEQR computes all eigenvalues and, optionally, eigenvectors of a */
+/* symmetric tridiagonal matrix using the implicit QL or QR method. */
+/* The eigenvectors of a full or band symmetric matrix can also be found */
+/* if DSYTRD or DSPTRD or DSBTRD has been used to reduce this matrix to */
+/* tridiagonal form. */
+
+/* Arguments */
+/* ========= */
+
+/* COMPZ (input) CHARACTER*1 */
+/* = 'N': Compute eigenvalues only. */
+/* = 'V': Compute eigenvalues and eigenvectors of the original */
+/* symmetric matrix. On entry, Z must contain the */
+/* orthogonal matrix used to reduce the original matrix */
+/* to tridiagonal form. */
+/* = 'I': Compute eigenvalues and eigenvectors of the */
+/* tridiagonal matrix. Z is initialized to the identity */
+/* matrix. */
+
+/* N (input) INTEGER */
+/* The order of the matrix. N >= 0. */
+
+/* D (input/output) DOUBLE PRECISION array, dimension (N) */
+/* On entry, the diagonal elements of the tridiagonal matrix. */
+/* On exit, if INFO = 0, the eigenvalues in ascending order. */
+
+/* E (input/output) DOUBLE PRECISION array, dimension (N-1) */
+/* On entry, the (n-1) subdiagonal elements of the tridiagonal */
+/* matrix. */
+/* On exit, E has been destroyed. */
+
+/* Z (input/output) DOUBLE PRECISION array, dimension (LDZ, N) */
+/* On entry, if COMPZ = 'V', then Z contains the orthogonal */
+/* matrix used in the reduction to tridiagonal form. */
+/* On exit, if INFO = 0, then if COMPZ = 'V', Z contains the */
+/* orthonormal eigenvectors of the original symmetric matrix, */
+/* and if COMPZ = 'I', Z contains the orthonormal eigenvectors */
+/* of the symmetric tridiagonal matrix. */
+/* If COMPZ = 'N', then Z is not referenced. */
+
+/* LDZ (input) INTEGER */
+/* The leading dimension of the array Z. LDZ >= 1, and if */
+/* eigenvectors are desired, then LDZ >= max(1,N). */
+
+/* WORK (workspace) DOUBLE PRECISION array, dimension (max(1,2*N-2)) */
+/* If COMPZ = 'N', then WORK is not referenced. */
+
+/* INFO (output) INTEGER */
+/* = 0: successful exit */
+/* < 0: if INFO = -i, the i-th argument had an illegal value */
+/* > 0: the algorithm has failed to find all the eigenvalues in */
+/* a total of 30*N iterations; if INFO = i, then i */
+/* elements of E have not converged to zero; on exit, D */
+/* and E contain the elements of a symmetric tridiagonal */
+/* matrix which is orthogonally similar to the original */
+/* matrix. */
+
+/* ===================================================================== */
+
+/* .. Parameters .. */
+/* .. */
+/* .. Local Scalars .. */
+/* .. */
+/* .. External Functions .. */
+/* .. */
+/* .. External Subroutines .. */
+/* .. */
+/* .. Intrinsic Functions .. */
+/* .. */
+/* .. Executable Statements .. */
+
+/* Test the input parameters. */
+
+ /* Parameter adjustments */
+ --d__;
+ --e;
+ z_dim1 = *ldz;
+ z_offset = 1 + z_dim1;
+ z__ -= z_offset;
+ --work;
+
+ /* Function Body */
+ *info = 0;
+
+ if (lsame_(compz, "N")) {
+ icompz = 0;
+ } else if (lsame_(compz, "V")) {
+ icompz = 1;
+ } else if (lsame_(compz, "I")) {
+ icompz = 2;
+ } else {
+ icompz = -1;
+ }
+ if (icompz < 0) {
+ *info = -1;
+ } else if (*n < 0) {
+ *info = -2;
+ } else if (*ldz < 1 || icompz > 0 && *ldz < max(1,*n)) {
+ *info = -6;
+ }
+ if (*info != 0) {
+ i__1 = -(*info);
+ xerbla_("DSTEQR", &i__1);
+ return 0;
+ }
+
+/* Quick return if possible */
+
+ if (*n == 0) {
+ return 0;
+ }
+
+ if (*n == 1) {
+ if (icompz == 2) {
+ z__[z_dim1 + 1] = 1.;
+ }
+ return 0;
+ }
+
+/* Determine the unit roundoff and over/underflow thresholds. */
+
+ eps = dlamch_("E");
+/* Computing 2nd power */
+ d__1 = eps;
+ eps2 = d__1 * d__1;
+ safmin = dlamch_("S");
+ safmax = 1. / safmin;
+ ssfmax = sqrt(safmax) / 3.;
+ ssfmin = sqrt(safmin) / eps2;
+
+/* Compute the eigenvalues and eigenvectors of the tridiagonal */
+/* matrix. */
+
+ if (icompz == 2) {
+ dlaset_("Full", n, n, &c_b9, &c_b10, &z__[z_offset], ldz);
+ }
+
+ nmaxit = *n * 30;
+ jtot = 0;
+
+/* Determine where the matrix splits and choose QL or QR iteration */
+/* for each block, according to whether top or bottom diagonal */
+/* element is smaller. */
+
+ l1 = 1;
+ nm1 = *n - 1;
+
+L10:
+ if (l1 > *n) {
+ goto L160;
+ }
+ if (l1 > 1) {
+ e[l1 - 1] = 0.;
+ }
+ if (l1 <= nm1) {
+ i__1 = nm1;
+ for (m = l1; m <= i__1; ++m) {
+ tst = (d__1 = e[m], abs(d__1));
+ if (tst == 0.) {
+ goto L30;
+ }
+ if (tst <= sqrt((d__1 = d__[m], abs(d__1))) * sqrt((d__2 = d__[m
+ + 1], abs(d__2))) * eps) {
+ e[m] = 0.;
+ goto L30;
+ }
+/* L20: */
+ }
+ }
+ m = *n;
+
+L30:
+ l = l1;
+ lsv = l;
+ lend = m;
+ lendsv = lend;
+ l1 = m + 1;
+ if (lend == l) {
+ goto L10;
+ }
+
+/* Scale submatrix in rows and columns L to LEND */
+
+ i__1 = lend - l + 1;
+ anorm = dlanst_("I", &i__1, &d__[l], &e[l]);
+ iscale = 0;
+ if (anorm == 0.) {
+ goto L10;
+ }
+ if (anorm > ssfmax) {
+ iscale = 1;
+ i__1 = lend - l + 1;
+ dlascl_("G", &c__0, &c__0, &anorm, &ssfmax, &i__1, &c__1, &d__[l], n,
+ info);
+ i__1 = lend - l;
+ dlascl_("G", &c__0, &c__0, &anorm, &ssfmax, &i__1, &c__1, &e[l], n,
+ info);
+ } else if (anorm < ssfmin) {
+ iscale = 2;
+ i__1 = lend - l + 1;
+ dlascl_("G", &c__0, &c__0, &anorm, &ssfmin, &i__1, &c__1, &d__[l], n,
+ info);
+ i__1 = lend - l;
+ dlascl_("G", &c__0, &c__0, &anorm, &ssfmin, &i__1, &c__1, &e[l], n,
+ info);
+ }
+
+/* Choose between QL and QR iteration */
+
+ if ((d__1 = d__[lend], abs(d__1)) < (d__2 = d__[l], abs(d__2))) {
+ lend = lsv;
+ l = lendsv;
+ }
+
+ if (lend > l) {
+
+/* QL Iteration */
+
+/* Look for small subdiagonal element. */
+
+L40:
+ if (l != lend) {
+ lendm1 = lend - 1;
+ i__1 = lendm1;
+ for (m = l; m <= i__1; ++m) {
+/* Computing 2nd power */
+ d__2 = (d__1 = e[m], abs(d__1));
+ tst = d__2 * d__2;
+ if (tst <= eps2 * (d__1 = d__[m], abs(d__1)) * (d__2 = d__[m
+ + 1], abs(d__2)) + safmin) {
+ goto L60;
+ }
+/* L50: */
+ }
+ }
+
+ m = lend;
+
+L60:
+ if (m < lend) {
+ e[m] = 0.;
+ }
+ p = d__[l];
+ if (m == l) {
+ goto L80;
+ }
+
+/* If remaining matrix is 2-by-2, use DLAE2 or SLAEV2 */
+/* to compute its eigensystem. */
+
+ if (m == l + 1) {
+ if (icompz > 0) {
+ dlaev2_(&d__[l], &e[l], &d__[l + 1], &rt1, &rt2, &c__, &s);
+ work[l] = c__;
+ work[*n - 1 + l] = s;
+ dlasr_("R", "V", "B", n, &c__2, &work[l], &work[*n - 1 + l], &
+ z__[l * z_dim1 + 1], ldz);
+ } else {
+ dlae2_(&d__[l], &e[l], &d__[l + 1], &rt1, &rt2);
+ }
+ d__[l] = rt1;
+ d__[l + 1] = rt2;
+ e[l] = 0.;
+ l += 2;
+ if (l <= lend) {
+ goto L40;
+ }
+ goto L140;
+ }
+
+ if (jtot == nmaxit) {
+ goto L140;
+ }
+ ++jtot;
+
+/* Form shift. */
+
+ g = (d__[l + 1] - p) / (e[l] * 2.);
+ r__ = dlapy2_(&g, &c_b10);
+ g = d__[m] - p + e[l] / (g + d_sign(&r__, &g));
+
+ s = 1.;
+ c__ = 1.;
+ p = 0.;
+
+/* Inner loop */
+
+ mm1 = m - 1;
+ i__1 = l;
+ for (i__ = mm1; i__ >= i__1; --i__) {
+ f = s * e[i__];
+ b = c__ * e[i__];
+ dlartg_(&g, &f, &c__, &s, &r__);
+ if (i__ != m - 1) {
+ e[i__ + 1] = r__;
+ }
+ g = d__[i__ + 1] - p;
+ r__ = (d__[i__] - g) * s + c__ * 2. * b;
+ p = s * r__;
+ d__[i__ + 1] = g + p;
+ g = c__ * r__ - b;
+
+/* If eigenvectors are desired, then save rotations. */
+
+ if (icompz > 0) {
+ work[i__] = c__;
+ work[*n - 1 + i__] = -s;
+ }
+
+/* L70: */
+ }
+
+/* If eigenvectors are desired, then apply saved rotations. */
+
+ if (icompz > 0) {
+ mm = m - l + 1;
+ dlasr_("R", "V", "B", n, &mm, &work[l], &work[*n - 1 + l], &z__[l
+ * z_dim1 + 1], ldz);
+ }
+
+ d__[l] -= p;
+ e[l] = g;
+ goto L40;
+
+/* Eigenvalue found. */
+
+L80:
+ d__[l] = p;
+
+ ++l;
+ if (l <= lend) {
+ goto L40;
+ }
+ goto L140;
+
+ } else {
+
+/* QR Iteration */
+
+/* Look for small superdiagonal element. */
+
+L90:
+ if (l != lend) {
+ lendp1 = lend + 1;
+ i__1 = lendp1;
+ for (m = l; m >= i__1; --m) {
+/* Computing 2nd power */
+ d__2 = (d__1 = e[m - 1], abs(d__1));
+ tst = d__2 * d__2;
+ if (tst <= eps2 * (d__1 = d__[m], abs(d__1)) * (d__2 = d__[m
+ - 1], abs(d__2)) + safmin) {
+ goto L110;
+ }
+/* L100: */
+ }
+ }
+
+ m = lend;
+
+L110:
+ if (m > lend) {
+ e[m - 1] = 0.;
+ }
+ p = d__[l];
+ if (m == l) {
+ goto L130;
+ }
+
+/* If remaining matrix is 2-by-2, use DLAE2 or SLAEV2 */
+/* to compute its eigensystem. */
+
+ if (m == l - 1) {
+ if (icompz > 0) {
+ dlaev2_(&d__[l - 1], &e[l - 1], &d__[l], &rt1, &rt2, &c__, &s)
+ ;
+ work[m] = c__;
+ work[*n - 1 + m] = s;
+ dlasr_("R", "V", "F", n, &c__2, &work[m], &work[*n - 1 + m], &
+ z__[(l - 1) * z_dim1 + 1], ldz);
+ } else {
+ dlae2_(&d__[l - 1], &e[l - 1], &d__[l], &rt1, &rt2);
+ }
+ d__[l - 1] = rt1;
+ d__[l] = rt2;
+ e[l - 1] = 0.;
+ l += -2;
+ if (l >= lend) {
+ goto L90;
+ }
+ goto L140;
+ }
+
+ if (jtot == nmaxit) {
+ goto L140;
+ }
+ ++jtot;
+
+/* Form shift. */
+
+ g = (d__[l - 1] - p) / (e[l - 1] * 2.);
+ r__ = dlapy2_(&g, &c_b10);
+ g = d__[m] - p + e[l - 1] / (g + d_sign(&r__, &g));
+
+ s = 1.;
+ c__ = 1.;
+ p = 0.;
+
+/* Inner loop */
+
+ lm1 = l - 1;
+ i__1 = lm1;
+ for (i__ = m; i__ <= i__1; ++i__) {
+ f = s * e[i__];
+ b = c__ * e[i__];
+ dlartg_(&g, &f, &c__, &s, &r__);
+ if (i__ != m) {
+ e[i__ - 1] = r__;
+ }
+ g = d__[i__] - p;
+ r__ = (d__[i__ + 1] - g) * s + c__ * 2. * b;
+ p = s * r__;
+ d__[i__] = g + p;
+ g = c__ * r__ - b;
+
+/* If eigenvectors are desired, then save rotations. */
+
+ if (icompz > 0) {
+ work[i__] = c__;
+ work[*n - 1 + i__] = s;
+ }
+
+/* L120: */
+ }
+
+/* If eigenvectors are desired, then apply saved rotations. */
+
+ if (icompz > 0) {
+ mm = l - m + 1;
+ dlasr_("R", "V", "F", n, &mm, &work[m], &work[*n - 1 + m], &z__[m
+ * z_dim1 + 1], ldz);
+ }
+
+ d__[l] -= p;
+ e[lm1] = g;
+ goto L90;
+
+/* Eigenvalue found. */
+
+L130:
+ d__[l] = p;
+
+ --l;
+ if (l >= lend) {
+ goto L90;
+ }
+ goto L140;
+
+ }
+
+/* Undo scaling if necessary */
+
+L140:
+ if (iscale == 1) {
+ i__1 = lendsv - lsv + 1;
+ dlascl_("G", &c__0, &c__0, &ssfmax, &anorm, &i__1, &c__1, &d__[lsv],
+ n, info);
+ i__1 = lendsv - lsv;
+ dlascl_("G", &c__0, &c__0, &ssfmax, &anorm, &i__1, &c__1, &e[lsv], n,
+ info);
+ } else if (iscale == 2) {
+ i__1 = lendsv - lsv + 1;
+ dlascl_("G", &c__0, &c__0, &ssfmin, &anorm, &i__1, &c__1, &d__[lsv],
+ n, info);
+ i__1 = lendsv - lsv;
+ dlascl_("G", &c__0, &c__0, &ssfmin, &anorm, &i__1, &c__1, &e[lsv], n,
+ info);
+ }
+
+/* Check for no convergence to an eigenvalue after a total */
+/* of N*MAXIT iterations. */
+
+ if (jtot < nmaxit) {
+ goto L10;
+ }
+ i__1 = *n - 1;
+ for (i__ = 1; i__ <= i__1; ++i__) {
+ if (e[i__] != 0.) {
+ ++(*info);
+ }
+/* L150: */
+ }
+ goto L190;
+
+/* Order eigenvalues and eigenvectors. */
+
+L160:
+ if (icompz == 0) {
+
+/* Use Quick Sort */
+
+ dlasrt_("I", n, &d__[1], info);
+
+ } else {
+
+/* Use Selection Sort to minimize swaps of eigenvectors */
+
+ i__1 = *n;
+ for (ii = 2; ii <= i__1; ++ii) {
+ i__ = ii - 1;
+ k = i__;
+ p = d__[i__];
+ i__2 = *n;
+ for (j = ii; j <= i__2; ++j) {
+ if (d__[j] < p) {
+ k = j;
+ p = d__[j];
+ }
+/* L170: */
+ }
+ if (k != i__) {
+ d__[k] = d__[i__];
+ d__[i__] = p;
+ dswap_(n, &z__[i__ * z_dim1 + 1], &c__1, &z__[k * z_dim1 + 1],
+ &c__1);
+ }
+/* L180: */
+ }
+ }
+
+L190:
+ return 0;
+
+/* End of DSTEQR */
+
+} /* dsteqr_ */
projects / opencv / blobdiff