101 lines
3.2 KiB
C++
101 lines
3.2 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 integer c__2 = 2;
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static integer c__0 = 0;
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int dlasq1_(integer *n, doublereal *d__, doublereal *e, doublereal *work, integer *info)
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{
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integer i__1, i__2;
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doublereal d__1, d__2, d__3;
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double sqrt(doublereal);
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integer i__;
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doublereal eps;
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extern int dlas2_(doublereal *, doublereal *, doublereal *, doublereal *, doublereal *);
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doublereal scale;
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integer iinfo;
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doublereal sigmn;
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extern int dcopy_(integer *, doublereal *, integer *, doublereal *, integer *);
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doublereal sigmx;
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extern int dlasq2_(integer *, doublereal *, integer *);
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extern doublereal dlamch_(char *, ftnlen);
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extern int dlascl_(char *, integer *, integer *, doublereal *, doublereal *, integer *,
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integer *, doublereal *, integer *, integer *, ftnlen);
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doublereal safmin;
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extern int xerbla_(char *, integer *, ftnlen),
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dlasrt_(char *, integer *, doublereal *, integer *, ftnlen);
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--work;
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--e;
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--d__;
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*info = 0;
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if (*n < 0) {
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*info = -1;
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i__1 = -(*info);
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xerbla_((char *)"DLASQ1", &i__1, (ftnlen)6);
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return 0;
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} else if (*n == 0) {
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return 0;
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} else if (*n == 1) {
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d__[1] = abs(d__[1]);
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return 0;
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} else if (*n == 2) {
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dlas2_(&d__[1], &e[1], &d__[2], &sigmn, &sigmx);
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d__[1] = sigmx;
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d__[2] = sigmn;
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return 0;
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}
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sigmx = 0.;
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i__1 = *n - 1;
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for (i__ = 1; i__ <= i__1; ++i__) {
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d__[i__] = (d__1 = d__[i__], abs(d__1));
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d__2 = sigmx, d__3 = (d__1 = e[i__], abs(d__1));
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sigmx = max(d__2, d__3);
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}
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d__[*n] = (d__1 = d__[*n], abs(d__1));
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if (sigmx == 0.) {
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dlasrt_((char *)"D", n, &d__[1], &iinfo, (ftnlen)1);
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return 0;
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}
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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d__1 = sigmx, d__2 = d__[i__];
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sigmx = max(d__1, d__2);
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}
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eps = dlamch_((char *)"Precision", (ftnlen)9);
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safmin = dlamch_((char *)"Safe minimum", (ftnlen)12);
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scale = sqrt(eps / safmin);
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dcopy_(n, &d__[1], &c__1, &work[1], &c__2);
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i__1 = *n - 1;
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dcopy_(&i__1, &e[1], &c__1, &work[2], &c__2);
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i__1 = (*n << 1) - 1;
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i__2 = (*n << 1) - 1;
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dlascl_((char *)"G", &c__0, &c__0, &sigmx, &scale, &i__1, &c__1, &work[1], &i__2, &iinfo, (ftnlen)1);
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i__1 = (*n << 1) - 1;
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for (i__ = 1; i__ <= i__1; ++i__) {
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d__1 = work[i__];
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work[i__] = d__1 * d__1;
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}
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work[*n * 2] = 0.;
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dlasq2_(n, &work[1], info);
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if (*info == 0) {
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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d__[i__] = sqrt(work[i__]);
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}
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dlascl_((char *)"G", &c__0, &c__0, &scale, &sigmx, n, &c__1, &d__[1], n, &iinfo, (ftnlen)1);
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} else if (*info == 2) {
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i__1 = *n;
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for (i__ = 1; i__ <= i__1; ++i__) {
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d__[i__] = sqrt(work[(i__ << 1) - 1]);
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e[i__] = sqrt(work[i__ * 2]);
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}
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dlascl_((char *)"G", &c__0, &c__0, &scale, &sigmx, n, &c__1, &d__[1], n, &iinfo, (ftnlen)1);
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dlascl_((char *)"G", &c__0, &c__0, &scale, &sigmx, n, &c__1, &e[1], n, &iinfo, (ftnlen)1);
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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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