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SUBROUTINE <a name="CTRCON.1"></a><a href="ctrcon.f.html#CTRCON.1">CTRCON</a>( NORM, UPLO, DIAG, N, A, LDA, 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 DIAG, NORM, UPLO
INTEGER INFO, LDA, N
REAL RCOND
<span class="comment">*</span><span class="comment"> ..
</span><span class="comment">*</span><span class="comment"> .. Array Arguments ..
</span> REAL RWORK( * )
COMPLEX A( LDA, * ), 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="CTRCON.23"></a><a href="ctrcon.f.html#CTRCON.1">CTRCON</a> estimates the reciprocal of the condition number of a
</span><span class="comment">*</span><span class="comment"> triangular matrix A, in either the 1-norm or the infinity-norm.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> The norm of A is computed and an estimate is obtained for
</span><span class="comment">*</span><span class="comment"> norm(inv(A)), then the reciprocal of the condition number is
</span><span class="comment">*</span><span class="comment"> 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"> UPLO (input) CHARACTER*1
</span><span class="comment">*</span><span class="comment"> = 'U': A is upper triangular;
</span><span class="comment">*</span><span class="comment"> = 'L': A is lower triangular.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> DIAG (input) CHARACTER*1
</span><span class="comment">*</span><span class="comment"> = 'N': A is non-unit triangular;
</span><span class="comment">*</span><span class="comment"> = 'U': A is unit triangular.
</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"> A (input) COMPLEX array, dimension (LDA,N)
</span><span class="comment">*</span><span class="comment"> The triangular matrix A. If UPLO = 'U', the leading N-by-N
</span><span class="comment">*</span><span class="comment"> upper triangular part of the array A contains the upper
</span><span class="comment">*</span><span class="comment"> triangular matrix, and the strictly lower triangular part of
</span><span class="comment">*</span><span class="comment"> A is not referenced. If UPLO = 'L', the leading N-by-N lower
</span><span class="comment">*</span><span class="comment"> triangular part of the array A contains the lower triangular
</span><span class="comment">*</span><span class="comment"> matrix, and the strictly upper triangular part of A is not
</span><span class="comment">*</span><span class="comment"> referenced. If DIAG = 'U', the diagonal elements of A are
</span><span class="comment">*</span><span class="comment"> also not referenced and are assumed to be 1.
</span><span class="comment">*</span><span class="comment">
</span><span class="comment">*</span><span class="comment"> LDA (input) INTEGER
</span><span class="comment">*</span><span class="comment"> The leading dimension of the array A. LDA >= max(1,N).
</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 NOUNIT, ONENRM, UPPER
CHARACTER NORMIN
INTEGER IX, KASE, KASE1
REAL AINVNM, ANORM, SCALE, SMLNUM, XNORM
COMPLEX 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.93"></a><a href="lsame.f.html#LSAME.1">LSAME</a>
INTEGER ICAMAX
REAL <a name="CLANTR.95"></a><a href="clantr.f.html#CLANTR.1">CLANTR</a>, <a name="SLAMCH.95"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
EXTERNAL <a name="LSAME.96"></a><a href="lsame.f.html#LSAME.1">LSAME</a>, ICAMAX, <a name="CLANTR.96"></a><a href="clantr.f.html#CLANTR.1">CLANTR</a>, <a name="SLAMCH.96"></a><a href="slamch.f.html#SLAMCH.1">SLAMCH</a>
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