sptsv.c
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00001 /* sptsv.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 /* Subroutine */ int sptsv_(integer *n, integer *nrhs, real *d__, real *e, 
00017         real *b, integer *ldb, integer *info)
00018 {
00019     /* System generated locals */
00020     integer b_dim1, b_offset, i__1;
00021 
00022     /* Local variables */
00023     extern /* Subroutine */ int xerbla_(char *, integer *), spttrf_(
00024             integer *, real *, real *, integer *), spttrs_(integer *, integer 
00025             *, real *, real *, real *, integer *, integer *);
00026 
00027 
00028 /*  -- LAPACK routine (version 3.2) -- */
00029 /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
00030 /*     November 2006 */
00031 
00032 /*     .. Scalar Arguments .. */
00033 /*     .. */
00034 /*     .. Array Arguments .. */
00035 /*     .. */
00036 
00037 /*  Purpose */
00038 /*  ======= */
00039 
00040 /*  SPTSV computes the solution to a real system of linear equations */
00041 /*  A*X = B, where A is an N-by-N symmetric positive definite tridiagonal */
00042 /*  matrix, and X and B are N-by-NRHS matrices. */
00043 
00044 /*  A is factored as A = L*D*L**T, and the factored form of A is then */
00045 /*  used to solve the system of equations. */
00046 
00047 /*  Arguments */
00048 /*  ========= */
00049 
00050 /*  N       (input) INTEGER */
00051 /*          The order of the matrix A.  N >= 0. */
00052 
00053 /*  NRHS    (input) INTEGER */
00054 /*          The number of right hand sides, i.e., the number of columns */
00055 /*          of the matrix B.  NRHS >= 0. */
00056 
00057 /*  D       (input/output) REAL array, dimension (N) */
00058 /*          On entry, the n diagonal elements of the tridiagonal matrix */
00059 /*          A.  On exit, the n diagonal elements of the diagonal matrix */
00060 /*          D from the factorization A = L*D*L**T. */
00061 
00062 /*  E       (input/output) REAL array, dimension (N-1) */
00063 /*          On entry, the (n-1) subdiagonal elements of the tridiagonal */
00064 /*          matrix A.  On exit, the (n-1) subdiagonal elements of the */
00065 /*          unit bidiagonal factor L from the L*D*L**T factorization of */
00066 /*          A.  (E can also be regarded as the superdiagonal of the unit */
00067 /*          bidiagonal factor U from the U**T*D*U factorization of A.) */
00068 
00069 /*  B       (input/output) REAL array, dimension (LDB,NRHS) */
00070 /*          On entry, the N-by-NRHS right hand side matrix B. */
00071 /*          On exit, if INFO = 0, the N-by-NRHS solution matrix X. */
00072 
00073 /*  LDB     (input) INTEGER */
00074 /*          The leading dimension of the array B.  LDB >= max(1,N). */
00075 
00076 /*  INFO    (output) INTEGER */
00077 /*          = 0:  successful exit */
00078 /*          < 0:  if INFO = -i, the i-th argument had an illegal value */
00079 /*          > 0:  if INFO = i, the leading minor of order i is not */
00080 /*                positive definite, and the solution has not been */
00081 /*                computed.  The factorization has not been completed */
00082 /*                unless i = N. */
00083 
00084 /*  ===================================================================== */
00085 
00086 /*     .. External Subroutines .. */
00087 /*     .. */
00088 /*     .. Intrinsic Functions .. */
00089 /*     .. */
00090 /*     .. Executable Statements .. */
00091 
00092 /*     Test the input parameters. */
00093 
00094     /* Parameter adjustments */
00095     --d__;
00096     --e;
00097     b_dim1 = *ldb;
00098     b_offset = 1 + b_dim1;
00099     b -= b_offset;
00100 
00101     /* Function Body */
00102     *info = 0;
00103     if (*n < 0) {
00104         *info = -1;
00105     } else if (*nrhs < 0) {
00106         *info = -2;
00107     } else if (*ldb < max(1,*n)) {
00108         *info = -6;
00109     }
00110     if (*info != 0) {
00111         i__1 = -(*info);
00112         xerbla_("SPTSV ", &i__1);
00113         return 0;
00114     }
00115 
00116 /*     Compute the L*D*L' (or U'*D*U) factorization of A. */
00117 
00118     spttrf_(n, &d__[1], &e[1], info);
00119     if (*info == 0) {
00120 
00121 /*        Solve the system A*X = B, overwriting B with X. */
00122 
00123         spttrs_(n, nrhs, &d__[1], &e[1], &b[b_offset], ldb, info);
00124     }
00125     return 0;
00126 
00127 /*     End of SPTSV */
00128 
00129 } /* sptsv_ */


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autogenerated on Sat Jun 8 2019 18:56:13