.TH "SRC/cgtcon.f" 3 "Version 3.12.0" "LAPACK" \" -*- nroff -*-
.ad l
.nh
.SH NAME
SRC/cgtcon.f
.SH SYNOPSIS
.br
.PP
.SS "Functions/Subroutines"

.in +1c
.ti -1c
.RI "subroutine \fBcgtcon\fP (norm, n, dl, d, du, du2, ipiv, anorm, rcond, work, info)"
.br
.RI "\fBCGTCON\fP "
.in -1c
.SH "Function/Subroutine Documentation"
.PP 
.SS "subroutine cgtcon (character norm, integer n, complex, dimension( * ) dl, complex, dimension( * ) d, complex, dimension( * ) du, complex, dimension( * ) du2, integer, dimension( * ) ipiv, real anorm, real rcond, complex, dimension( * ) work, integer info)"

.PP
\fBCGTCON\fP  
.PP
\fBPurpose:\fP
.RS 4

.PP
.nf
 CGTCON estimates the reciprocal of the condition number of a complex
 tridiagonal matrix A using the LU factorization as computed by
 CGTTRF\&.

 An estimate is obtained for norm(inv(A)), and the reciprocal of the
 condition number is computed as RCOND = 1 / (ANORM * norm(inv(A)))\&.
.fi
.PP
 
.RE
.PP
\fBParameters\fP
.RS 4
\fINORM\fP 
.PP
.nf
          NORM is CHARACTER*1
          Specifies whether the 1-norm condition number or the
          infinity-norm condition number is required:
          = '1' or 'O':  1-norm;
          = 'I':         Infinity-norm\&.
.fi
.PP
.br
\fIN\fP 
.PP
.nf
          N is INTEGER
          The order of the matrix A\&.  N >= 0\&.
.fi
.PP
.br
\fIDL\fP 
.PP
.nf
          DL is COMPLEX array, dimension (N-1)
          The (n-1) multipliers that define the matrix L from the
          LU factorization of A as computed by CGTTRF\&.
.fi
.PP
.br
\fID\fP 
.PP
.nf
          D is COMPLEX array, dimension (N)
          The n diagonal elements of the upper triangular matrix U from
          the LU factorization of A\&.
.fi
.PP
.br
\fIDU\fP 
.PP
.nf
          DU is COMPLEX array, dimension (N-1)
          The (n-1) elements of the first superdiagonal of U\&.
.fi
.PP
.br
\fIDU2\fP 
.PP
.nf
          DU2 is COMPLEX array, dimension (N-2)
          The (n-2) elements of the second superdiagonal of U\&.
.fi
.PP
.br
\fIIPIV\fP 
.PP
.nf
          IPIV is INTEGER array, dimension (N)
          The pivot indices; for 1 <= i <= n, row i of the matrix was
          interchanged with row IPIV(i)\&.  IPIV(i) will always be either
          i or i+1; IPIV(i) = i indicates a row interchange was not
          required\&.
.fi
.PP
.br
\fIANORM\fP 
.PP
.nf
          ANORM is REAL
          If NORM = '1' or 'O', the 1-norm of the original matrix A\&.
          If NORM = 'I', the infinity-norm of the original matrix A\&.
.fi
.PP
.br
\fIRCOND\fP 
.PP
.nf
          RCOND is REAL
          The reciprocal of the condition number of the matrix A,
          computed as RCOND = 1/(ANORM * AINVNM), where AINVNM is an
          estimate of the 1-norm of inv(A) computed in this routine\&.
.fi
.PP
.br
\fIWORK\fP 
.PP
.nf
          WORK is COMPLEX array, dimension (2*N)
.fi
.PP
.br
\fIINFO\fP 
.PP
.nf
          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
.fi
.PP
 
.RE
.PP
\fBAuthor\fP
.RS 4
Univ\&. of Tennessee 
.PP
Univ\&. of California Berkeley 
.PP
Univ\&. of Colorado Denver 
.PP
NAG Ltd\&. 
.RE
.PP

.PP
Definition at line \fB139\fP of file \fBcgtcon\&.f\fP\&.
.SH "Author"
.PP 
Generated automatically by Doxygen for LAPACK from the source code\&.