text: /* ctbtrs.f -- translated by f2c (version 20061008).
     You must link the resulting object file with libf2c:
  	on Microsoft Windows system, link with libf2c.lib;
  	on Linux or Unix systems, link with .../path/to/libf2c.a -lm
  	or, if you install libf2c.a in a standard place, with -lf2c -lm
  	-- in that order, at the end of the command line, as in
  		cc *.o -lf2c -lm
  	Source for libf2c is in /netlib/f2c/libf2c.zip, e.g.,
  
  		http://www.netlib.org/f2c/libf2c.zip
  */
  
  #include "f2c.h"
  #include "blaswrap.h"
  
  /* Table of constant values */
  
  static integer c__1 = 1;
  
  /* Subroutine */ int ctbtrs_(char *uplo, char *trans, char *diag, integer *n, 
  	integer *kd, integer *nrhs, complex *ab, integer *ldab, complex *b, 
  	integer *ldb, integer *info)
  {
      /* System generated locals */
      integer ab_dim1, ab_offset, b_dim1, b_offset, i__1, i__2;
  
      /* Local variables */
      integer j;
      extern logical lsame_(char *, char *);
      extern /* Subroutine */ int ctbsv_(char *, char *, char *, integer *, 
  	    integer *, complex *, integer *, complex *, integer *);
      logical upper;
      extern /* Subroutine */ int xerbla_(char *, integer *);
      logical nounit;
  
  
  /*  -- LAPACK routine (version 3.2) -- */
  /*     Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. */
  /*     November 2006 */
  
  /*     .. Scalar Arguments .. */
  /*     .. */
  /*     .. Array Arguments .. */
  /*     .. */
  
  /*  Purpose */
  /*  ======= */
  
  /*  CTBTRS solves a triangular system of the form */
  
  /*     A * X = B,  A**T * X = B,  or  A**H * X = B, */
  
  /*  where A is a triangular band matrix of order N, and B is an */
  /*  N-by-NRHS matrix.  A check is made to verify that A is nonsingular. */
  
  /*  Arguments */
  /*  ========= */
  
  /*  UPLO    (input) CHARACTER*1 */
  /*          = 'U':  A is upper triangular; */
  /*          = 'L':  A is lower triangular. */
  
  /*  TRANS   (input) CHARACTER*1 */
  /*          Specifies the form of the system of equations: */
  /*          = 'N':  A * X = B     (No transpose) */
  /*          = 'T':  A**T * X = B  (Transpose) */
  /*          = 'C':  A**H * X = B  (Conjugate transpose) */
  
  /*  DIAG    (input) CHARACTER*1 */
  /*          = 'N':  A is non-unit triangular; */
  /*          = 'U':  A is unit triangular. */
  
  /*  N       (input) INTEGER */
  /*          The order of the matrix A.  N >= 0. */
  
  /*  KD      (input) INTEGER */
  /*          The number of superdiagonals or subdiagonals of the */
  /*          triangular band matrix A.  KD >= 0. */
  
  /*  NRHS    (input) INTEGER */
  /*          The number of right hand sides, i.e., the number of columns */
  /*          of the matrix B.  NRHS >= 0. */
  
  /*  AB      (input) COMPLEX array, dimension (LDAB,N) */
  /*          The upper or lower triangular band matrix A, stored in the */
  /*          first kd+1 rows of AB.  The j-th column of A is stored */
  /*          in the j-th column of the array AB as follows: */
  /*          if UPLO = 'U', AB(kd+1+i-j,j) = A(i,j) for max(1,j-kd)<=i<=j; */
  /*          if UPLO = 'L', AB(1+i-j,j)    = A(i,j) for j<=i<=min(n,j+kd). */
  /*          If DIAG = 'U', the diagonal elements of A are not referenced */
  /*          and are assumed to be 1. */
  
  /*  LDAB    (input) INTEGER */
  /*          The leading dimension of the array AB.  LDAB >= KD+1. */
  
  /*  B       (input/output) COMPLEX array, dimension (LDB,NRHS) */
  /*          On entry, the right hand side matrix B. */
  /*          On exit, if INFO = 0, the solution matrix X. */
  
  /*  LDB     (input) INTEGER */
  /*          The leading dimension of the array B.  LDB >= max(1,N). */
  
  /*  INFO    (output) INTEGER */
  /*          = 0:  successful exit */
  /*          < 0:  if INFO = -i, the i-th argument had an illegal value */
  /*          > 0:  if INFO = i, the i-th diagonal element of A is zero, */
  /*                indicating that the matrix is singular and the */
  /*                solutions X have not been computed. */
  
  /*  ===================================================================== */
  
  /*     .. Parameters .. */
  /*     .. */
  /*     .. Local Scalars .. */
  /*     .. */
  /*     .. External Functions .. */
  /*     .. */
  /*     .. External Subroutines .. */
  /*     .. */
  /*     .. Intrinsic Functions .. */
  /*     .. */
  /*     .. Executable Statements .. */
  
  /*     Test the input parameters. */
  
      /* Parameter adjustments */
      ab_dim1 = *ldab;
      ab_offset = 1 + ab_dim1;
      ab -= ab_offset;
      b_dim1 = *ldb;
      b_offset = 1 + b_dim1;
      b -= b_offset;
  
      /* Function Body */
      *info = 0;
      nounit = lsame_(diag, "N");
      upper = lsame_(uplo, "U");
      if (! upper && ! lsame_(uplo, "L")) {
  	*info = -1;
      } else if (! lsame_(trans, "N") && ! lsame_(trans, 
  	    "T") && ! lsame_(trans, "C")) {
  	*info = -2;
      } else if (! nounit && ! lsame_(diag, "U")) {
  	*info = -3;
      } else if (*n < 0) {
  	*info = -4;
      } else if (*kd < 0) {
  	*info = -5;
      } else if (*nrhs < 0) {
  	*info = -6;
      } else if (*ldab < *kd + 1) {
  	*info = -8;
      } else if (*ldb < max(1,*n)) {
  	*info = -10;
      }
      if (*info != 0) {
  	i__1 = -(*info);
  	xerbla_("CTBTRS", &i__1);
  	return 0;
      }
  
  /*     Quick return if possible */
  
      if (*n == 0) {
  	return 0;
      }
  
  /*     Check for singularity. */
  
      if (nounit) {
  	if (upper) {
  	    i__1 = *n;
  	    for (*info = 1; *info <= i__1; ++(*info)) {
  		i__2 = *kd + 1 + *info * ab_dim1;
  		if (ab[i__2].r == 0.f && ab[i__2].i == 0.f) {
  		    return 0;
  		}
  /* L10: */
  	    }
  	} else {
  	    i__1 = *n;
  	    for (*info = 1; *info <= i__1; ++(*info)) {
  		i__2 = *info * ab_dim1 + 1;
  		if (ab[i__2].r == 0.f && ab[i__2].i == 0.f) {
  		    return 0;
  		}
  /* L20: */
  	    }
  	}
      }
      *info = 0;
  
  /*     Solve A * X = B,  A**T * X = B,  or  A**H * X = B. */
  
      i__1 = *nrhs;
      for (j = 1; j <= i__1; ++j) {
  	ctbsv_(uplo, trans, diag, n, kd, &ab[ab_offset], ldab, &b[j * b_dim1 
  		+ 1], &c__1);
  /* L30: */
      }
  
      return 0;
  
  /*     End of CTBTRS */
  
  } /* ctbtrs_ */
  