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SUBROUTINE <a name="CGBCON.1"></a><a href="cgbcon.f.html#CGBCON.1">CGBCON</a>( NORM, N, KL, KU, AB, LDAB, IPIV, ANORM, RCOND,
$ WORK, RWORK, INFO )
<span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> -- LAPACK routine (version 3.1) --
</span><span class="comment">*</span><span class="comment"> Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd..
</span><span class="comment">*</span><span class="comment"> November 2006
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Modified to call <a name="CLACN2.8"></a><a href="clacn2.f.html#CLACN2.1">CLACN2</a> in place of <a name="CLACON.8"></a><a href="clacon.f.html#CLACON.1">CLACON</a>, 10 Feb 03, SJH.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> .. Scalar Arguments ..
</span> CHARACTER NORM
INTEGER INFO, KL, KU, LDAB, N
REAL ANORM, RCOND
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Array Arguments ..
</span> INTEGER IPIV( * )
REAL RWORK( * )
COMPLEX AB( LDAB, * ), WORK( * )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Purpose
</span><span class="comment">*</span><span class="comment"> =======
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> <a name="CGBCON.24"></a><a href="cgbcon.f.html#CGBCON.1">CGBCON</a> estimates the reciprocal of the condition number of a complex
</span><span class="comment">*</span><span class="comment"> general band matrix A, in either the 1-norm or the infinity-norm,
</span><span class="comment">*</span><span class="comment"> using the LU factorization computed by <a name="CGBTRF.26"></a><a href="cgbtrf.f.html#CGBTRF.1">CGBTRF</a>.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> An estimate is obtained for norm(inv(A)), and the reciprocal of the
</span><span class="comment">*</span><span class="comment"> condition number is computed as
</span><span class="comment">*</span><span class="comment"> RCOND = 1 / ( norm(A) * norm(inv(A)) ).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> Arguments
</span><span class="comment">*</span><span class="comment"> =========
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> NORM (input) CHARACTER*1
</span><span class="comment">*</span><span class="comment"> Specifies whether the 1-norm condition number or the
</span><span class="comment">*</span><span class="comment"> infinity-norm condition number is required:
</span><span class="comment">*</span><span class="comment"> = '1' or 'O': 1-norm;
</span><span class="comment">*</span><span class="comment"> = 'I': Infinity-norm.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> N (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The order of the matrix A. N >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> KL (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The number of subdiagonals within the band of A. KL >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> KU (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The number of superdiagonals within the band of A. KU >= 0.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> AB (input) COMPLEX array, dimension (LDAB,N)
</span><span class="comment">*</span><span class="comment"> Details of the LU factorization of the band matrix A, as
</span><span class="comment">*</span><span class="comment"> computed by <a name="CGBTRF.52"></a><a href="cgbtrf.f.html#CGBTRF.1">CGBTRF</a>. U is stored as an upper triangular band
</span><span class="comment">*</span><span class="comment"> matrix with KL+KU superdiagonals in rows 1 to KL+KU+1, and
</span><span class="comment">*</span><span class="comment"> the multipliers used during the factorization are stored in
</span><span class="comment">*</span><span class="comment"> rows KL+KU+2 to 2*KL+KU+1.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> LDAB (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The leading dimension of the array AB. LDAB >= 2*KL+KU+1.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> IPIV (input) INTEGER array, dimension (N)
</span><span class="comment">*</span><span class="comment"> The pivot indices; for 1 <= i <= N, row i of the matrix was
</span><span class="comment">*</span><span class="comment"> interchanged with row IPIV(i).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> ANORM (input) REAL
</span><span class="comment">*</span><span class="comment"> If NORM = '1' or 'O', the 1-norm of the original matrix A.
</span><span class="comment">*</span><span class="comment"> If NORM = 'I', the infinity-norm of the original matrix A.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> RCOND (output) REAL
</span><span class="comment">*</span><span class="comment"> The reciprocal of the condition number of the matrix A,
</span><span class="comment">*</span><span class="comment"> computed as RCOND = 1/(norm(A) * norm(inv(A))).
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> WORK (workspace) COMPLEX array, dimension (2*N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> RWORK (workspace) REAL array, dimension (N)
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> INFO (output) INTEGER
</span><span class="comment">*</span><span class="comment"> = 0: successful exit
</span><span class="comment">*</span><span class="comment"> < 0: if INFO = -i, the i-th argument had an illegal value
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> =====================================================================
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> .. Parameters ..
</span> REAL ONE, ZERO
PARAMETER ( ONE = 1.0E+0, ZERO = 0.0E+0 )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Local Scalars ..
</span> LOGICAL LNOTI, ONENRM
CHARACTER NORMIN
INTEGER IX, J, JP, KASE, KASE1, KD, LM
REAL AINVNM, SCALE, SMLNUM
COMPLEX T, ZDUM
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Local Arrays ..
</span> INTEGER ISAVE( 3 )
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. External Functions ..
</span> LOGICAL <a name="LSAME.97"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
INTEGER ICAMAX
REAL <a name="SLAMCH.99"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
COMPLEX CDOTC
EXTERNAL <a name="LSAME.101"></a><a href="lsame.f.html#LSAME.1">LSAME</a>, ICAMAX, <a name="SLAMCH.101"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>, CDOTC
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. External Subroutines ..
</span> EXTERNAL CAXPY, <a name="CLACN2.104"></a><a href="clacn2.f.html#CLACN2.1">CLACN2</a>, <a name="CLATBS.104"></a><a href="clatbs.f.html#CLATBS.1">CLATBS</a>, <a name="CSRSCL.104"></a><a href="csrscl.f.html#CSRSCL.1">CSRSCL</a>, <a name="XERBLA.104"></a><a href="xerbla.f.html#XERBLA.1">XERBLA</a>
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Intrinsic Functions ..
</span> INTRINSIC ABS, AIMAG, MIN, REAL
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Statement Functions ..
</span> REAL CABS1
<span class="comment">*</span><span class="comment"> ..
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