cspcon.c
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00001 /* cspcon.f -- translated by f2c (version 20061008).
00002    You must link the resulting object file with libf2c:
00003         on Microsoft Windows system, link with libf2c.lib;
00004         on Linux or Unix systems, link with .../path/to/libf2c.a -lm
00005         or, if you install libf2c.a in a standard place, with -lf2c -lm
00006         -- in that order, at the end of the command line, as in
00007                 cc *.o -lf2c -lm
00008         Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
00009 
00010                 http://www.netlib.org/f2c/libf2c.zip
00011 */
00012 
00013 #include "f2c.h"
00014 #include "blaswrap.h"
00015 
00016 /* Table of constant values */
00017 
00018 static integer c__1 = 1;
00019 
00020 /* Subroutine */ int cspcon_(char *uplo, integer *n, complex *ap, integer *
00021         ipiv, real *anorm, real *rcond, complex *work, integer *info)
00022 {
00023     /* System generated locals */
00024     integer i__1, i__2;
00025 
00026     /* Local variables */
00027     integer i__, ip, kase;
00028     extern logical lsame_(char *, char *);
00029     integer isave[3];
00030     logical upper;
00031     extern /* Subroutine */ int clacn2_(integer *, complex *, complex *, real 
00032             *, integer *, integer *), xerbla_(char *, integer *);
00033     real ainvnm;
00034     extern /* Subroutine */ int csptrs_(char *, integer *, integer *, complex 
00035             *, integer *, complex *, integer *, integer *);
00036 
00037 
00038 /*  -- LAPACK routine (version 3.2) -- */
00039 /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
00040 /*     November 2006 */
00041 
00042 /*     Modified to call CLACN2 in place of CLACON, 10 Feb 03, SJH. */
00043 
00044 /*     .. Scalar Arguments .. */
00045 /*     .. */
00046 /*     .. Array Arguments .. */
00047 /*     .. */
00048 
00049 /*  Purpose */
00050 /*  ======= */
00051 
00052 /*  CSPCON estimates the reciprocal of the condition number (in the */
00053 /*  1-norm) of a complex symmetric packed matrix A using the */
00054 /*  factorization A = U*D*U**T or A = L*D*L**T computed by CSPTRF. */
00055 
00056 /*  An estimate is obtained for norm(inv(A)), and the reciprocal of the */
00057 /*  condition number is computed as RCOND = 1 / (ANORM * norm(inv(A))). */
00058 
00059 /*  Arguments */
00060 /*  ========= */
00061 
00062 /*  UPLO    (input) CHARACTER*1 */
00063 /*          Specifies whether the details of the factorization are stored */
00064 /*          as an upper or lower triangular matrix. */
00065 /*          = 'U':  Upper triangular, form is A = U*D*U**T; */
00066 /*          = 'L':  Lower triangular, form is A = L*D*L**T. */
00067 
00068 /*  N       (input) INTEGER */
00069 /*          The order of the matrix A.  N >= 0. */
00070 
00071 /*  AP      (input) COMPLEX array, dimension (N*(N+1)/2) */
00072 /*          The block diagonal matrix D and the multipliers used to */
00073 /*          obtain the factor U or L as computed by CSPTRF, stored as a */
00074 /*          packed triangular matrix. */
00075 
00076 /*  IPIV    (input) INTEGER array, dimension (N) */
00077 /*          Details of the interchanges and the block structure of D */
00078 /*          as determined by CSPTRF. */
00079 
00080 /*  ANORM   (input) REAL */
00081 /*          The 1-norm of the original matrix A. */
00082 
00083 /*  RCOND   (output) REAL */
00084 /*          The reciprocal of the condition number of the matrix A, */
00085 /*          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an */
00086 /*          estimate of the 1-norm of inv(A) computed in this routine. */
00087 
00088 /*  WORK    (workspace) COMPLEX array, dimension (2*N) */
00089 
00090 /*  INFO    (output) INTEGER */
00091 /*          = 0:  successful exit */
00092 /*          < 0:  if INFO = -i, the i-th argument had an illegal value */
00093 
00094 /*  ===================================================================== */
00095 
00096 /*     .. Parameters .. */
00097 /*     .. */
00098 /*     .. Local Scalars .. */
00099 /*     .. */
00100 /*     .. Local Arrays .. */
00101 /*     .. */
00102 /*     .. External Functions .. */
00103 /*     .. */
00104 /*     .. External Subroutines .. */
00105 /*     .. */
00106 /*     .. Executable Statements .. */
00107 
00108 /*     Test the input parameters. */
00109 
00110     /* Parameter adjustments */
00111     --work;
00112     --ipiv;
00113     --ap;
00114 
00115     /* Function Body */
00116     *info = 0;
00117     upper = lsame_(uplo, "U");
00118     if (! upper && ! lsame_(uplo, "L")) {
00119         *info = -1;
00120     } else if (*n < 0) {
00121         *info = -2;
00122     } else if (*anorm < 0.f) {
00123         *info = -5;
00124     }
00125     if (*info != 0) {
00126         i__1 = -(*info);
00127         xerbla_("CSPCON", &i__1);
00128         return 0;
00129     }
00130 
00131 /*     Quick return if possible */
00132 
00133     *rcond = 0.f;
00134     if (*n == 0) {
00135         *rcond = 1.f;
00136         return 0;
00137     } else if (*anorm <= 0.f) {
00138         return 0;
00139     }
00140 
00141 /*     Check that the diagonal matrix D is nonsingular. */
00142 
00143     if (upper) {
00144 
00145 /*        Upper triangular storage: examine D from bottom to top */
00146 
00147         ip = *n * (*n + 1) / 2;
00148         for (i__ = *n; i__ >= 1; --i__) {
00149             i__1 = ip;
00150             if (ipiv[i__] > 0 && (ap[i__1].r == 0.f && ap[i__1].i == 0.f)) {
00151                 return 0;
00152             }
00153             ip -= i__;
00154 /* L10: */
00155         }
00156     } else {
00157 
00158 /*        Lower triangular storage: examine D from top to bottom. */
00159 
00160         ip = 1;
00161         i__1 = *n;
00162         for (i__ = 1; i__ <= i__1; ++i__) {
00163             i__2 = ip;
00164             if (ipiv[i__] > 0 && (ap[i__2].r == 0.f && ap[i__2].i == 0.f)) {
00165                 return 0;
00166             }
00167             ip = ip + *n - i__ + 1;
00168 /* L20: */
00169         }
00170     }
00171 
00172 /*     Estimate the 1-norm of the inverse. */
00173 
00174     kase = 0;
00175 L30:
00176     clacn2_(n, &work[*n + 1], &work[1], &ainvnm, &kase, isave);
00177     if (kase != 0) {
00178 
00179 /*        Multiply by inv(L*D*L') or inv(U*D*U'). */
00180 
00181         csptrs_(uplo, n, &c__1, &ap[1], &ipiv[1], &work[1], n, info);
00182         goto L30;
00183     }
00184 
00185 /*     Compute the estimate of the reciprocal condition number. */
00186 
00187     if (ainvnm != 0.f) {
00188         *rcond = 1.f / ainvnm / *anorm;
00189     }
00190 
00191     return 0;
00192 
00193 /*     End of CSPCON */
00194 
00195 } /* cspcon_ */


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autogenerated on Sat Jun 8 2019 18:55:33