99 lines
3.9 KiB
C++
99 lines
3.9 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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static integer c__1 = 1;
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static doublereal c_b8 = 0.;
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static doublereal c_b14 = -1.;
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int dsytd2_(char *uplo, integer *n, doublereal *a, integer *lda, doublereal *d__, doublereal *e,
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doublereal *tau, integer *info, ftnlen uplo_len)
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{
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integer a_dim1, a_offset, i__1, i__2, i__3;
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integer i__;
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extern doublereal ddot_(integer *, doublereal *, integer *, doublereal *, integer *);
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doublereal taui;
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extern int dsyr2_(char *, integer *, doublereal *, doublereal *, integer *, doublereal *,
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integer *, doublereal *, integer *, ftnlen);
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doublereal alpha;
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extern logical lsame_(char *, char *, ftnlen, ftnlen);
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extern int daxpy_(integer *, doublereal *, doublereal *, integer *, doublereal *, integer *);
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logical upper;
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extern int dsymv_(char *, integer *, doublereal *, doublereal *, integer *, doublereal *,
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integer *, doublereal *, doublereal *, integer *, ftnlen),
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dlarfg_(integer *, doublereal *, doublereal *, integer *, doublereal *),
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xerbla_(char *, integer *, ftnlen);
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a_dim1 = *lda;
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a_offset = 1 + a_dim1;
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a -= a_offset;
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--d__;
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--e;
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--tau;
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*info = 0;
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upper = lsame_(uplo, (char *)"U", (ftnlen)1, (ftnlen)1);
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if (!upper && !lsame_(uplo, (char *)"L", (ftnlen)1, (ftnlen)1)) {
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*info = -1;
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} else if (*n < 0) {
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*info = -2;
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} else if (*lda < max(1, *n)) {
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*info = -4;
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}
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if (*info != 0) {
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i__1 = -(*info);
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xerbla_((char *)"DSYTD2", &i__1, (ftnlen)6);
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return 0;
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}
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if (*n <= 0) {
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return 0;
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}
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if (upper) {
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for (i__ = *n - 1; i__ >= 1; --i__) {
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dlarfg_(&i__, &a[i__ + (i__ + 1) * a_dim1], &a[(i__ + 1) * a_dim1 + 1], &c__1, &taui);
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e[i__] = a[i__ + (i__ + 1) * a_dim1];
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if (taui != 0.) {
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a[i__ + (i__ + 1) * a_dim1] = 1.;
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dsymv_(uplo, &i__, &taui, &a[a_offset], lda, &a[(i__ + 1) * a_dim1 + 1], &c__1,
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&c_b8, &tau[1], &c__1, (ftnlen)1);
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alpha = taui * -.5 * ddot_(&i__, &tau[1], &c__1, &a[(i__ + 1) * a_dim1 + 1], &c__1);
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daxpy_(&i__, &alpha, &a[(i__ + 1) * a_dim1 + 1], &c__1, &tau[1], &c__1);
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dsyr2_(uplo, &i__, &c_b14, &a[(i__ + 1) * a_dim1 + 1], &c__1, &tau[1], &c__1,
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&a[a_offset], lda, (ftnlen)1);
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a[i__ + (i__ + 1) * a_dim1] = e[i__];
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}
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d__[i__ + 1] = a[i__ + 1 + (i__ + 1) * a_dim1];
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tau[i__] = taui;
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}
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d__[1] = a[a_dim1 + 1];
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} else {
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i__1 = *n - 1;
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for (i__ = 1; i__ <= i__1; ++i__) {
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i__2 = *n - i__;
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i__3 = i__ + 2;
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dlarfg_(&i__2, &a[i__ + 1 + i__ * a_dim1], &a[min(i__3, *n) + i__ * a_dim1], &c__1,
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&taui);
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e[i__] = a[i__ + 1 + i__ * a_dim1];
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if (taui != 0.) {
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a[i__ + 1 + i__ * a_dim1] = 1.;
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i__2 = *n - i__;
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dsymv_(uplo, &i__2, &taui, &a[i__ + 1 + (i__ + 1) * a_dim1], lda,
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&a[i__ + 1 + i__ * a_dim1], &c__1, &c_b8, &tau[i__], &c__1, (ftnlen)1);
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i__2 = *n - i__;
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alpha =
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taui * -.5 * ddot_(&i__2, &tau[i__], &c__1, &a[i__ + 1 + i__ * a_dim1], &c__1);
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i__2 = *n - i__;
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daxpy_(&i__2, &alpha, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[i__], &c__1);
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i__2 = *n - i__;
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dsyr2_(uplo, &i__2, &c_b14, &a[i__ + 1 + i__ * a_dim1], &c__1, &tau[i__], &c__1,
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&a[i__ + 1 + (i__ + 1) * a_dim1], lda, (ftnlen)1);
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a[i__ + 1 + i__ * a_dim1] = e[i__];
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}
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d__[i__] = a[i__ + i__ * a_dim1];
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tau[i__] = taui;
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}
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d__[*n] = a[*n + *n * a_dim1];
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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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