--- rpl/lapack/lapack/zsytf2.f 2010/01/26 15:22:46 1.1.1.1
+++ rpl/lapack/lapack/zsytf2.f 2018/05/29 07:18:37 1.19
@@ -1,9 +1,200 @@
+*> \brief \b ZSYTF2 computes the factorization of a real symmetric indefinite matrix, using the diagonal pivoting method (unblocked algorithm).
+*
+* =========== DOCUMENTATION ===========
+*
+* Online html documentation available at
+* http://www.netlib.org/lapack/explore-html/
+*
+*> \htmlonly
+*> Download ZSYTF2 + dependencies
+*>
+*> [TGZ]
+*>
+*> [ZIP]
+*>
+*> [TXT]
+*> \endhtmlonly
+*
+* Definition:
+* ===========
+*
+* SUBROUTINE ZSYTF2( UPLO, N, A, LDA, IPIV, INFO )
+*
+* .. Scalar Arguments ..
+* CHARACTER UPLO
+* INTEGER INFO, LDA, N
+* ..
+* .. Array Arguments ..
+* INTEGER IPIV( * )
+* COMPLEX*16 A( LDA, * )
+* ..
+*
+*
+*> \par Purpose:
+* =============
+*>
+*> \verbatim
+*>
+*> ZSYTF2 computes the factorization of a complex symmetric matrix A
+*> using the Bunch-Kaufman diagonal pivoting method:
+*>
+*> A = U*D*U**T or A = L*D*L**T
+*>
+*> where U (or L) is a product of permutation and unit upper (lower)
+*> triangular matrices, U**T is the transpose of U, and D is symmetric and
+*> block diagonal with 1-by-1 and 2-by-2 diagonal blocks.
+*>
+*> This is the unblocked version of the algorithm, calling Level 2 BLAS.
+*> \endverbatim
+*
+* Arguments:
+* ==========
+*
+*> \param[in] UPLO
+*> \verbatim
+*> UPLO is CHARACTER*1
+*> Specifies whether the upper or lower triangular part of the
+*> symmetric matrix A is stored:
+*> = 'U': Upper triangular
+*> = 'L': Lower triangular
+*> \endverbatim
+*>
+*> \param[in] N
+*> \verbatim
+*> N is INTEGER
+*> The order of the matrix A. N >= 0.
+*> \endverbatim
+*>
+*> \param[in,out] A
+*> \verbatim
+*> A is COMPLEX*16 array, dimension (LDA,N)
+*> On entry, the symmetric matrix A. If UPLO = 'U', the leading
+*> n-by-n upper triangular part of A contains the upper
+*> triangular part of the matrix A, and the strictly lower
+*> triangular part of A is not referenced. If UPLO = 'L', the
+*> leading n-by-n lower triangular part of A contains the lower
+*> triangular part of the matrix A, and the strictly upper
+*> triangular part of A is not referenced.
+*>
+*> On exit, the block diagonal matrix D and the multipliers used
+*> to obtain the factor U or L (see below for further details).
+*> \endverbatim
+*>
+*> \param[in] LDA
+*> \verbatim
+*> LDA is INTEGER
+*> The leading dimension of the array A. LDA >= max(1,N).
+*> \endverbatim
+*>
+*> \param[out] IPIV
+*> \verbatim
+*> IPIV is INTEGER array, dimension (N)
+*> Details of the interchanges and the block structure of D.
+*>
+*> If UPLO = 'U':
+*> If IPIV(k) > 0, then rows and columns k and IPIV(k) were
+*> interchanged and D(k,k) is a 1-by-1 diagonal block.
+*>
+*> If IPIV(k) = IPIV(k-1) < 0, then rows and columns
+*> k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k)
+*> is a 2-by-2 diagonal block.
+*>
+*> If UPLO = 'L':
+*> If IPIV(k) > 0, then rows and columns k and IPIV(k) were
+*> interchanged and D(k,k) is a 1-by-1 diagonal block.
+*>
+*> If IPIV(k) = IPIV(k+1) < 0, then rows and columns
+*> k+1 and -IPIV(k) were interchanged and D(k:k+1,k:k+1)
+*> is a 2-by-2 diagonal block.
+*> \endverbatim
+*>
+*> \param[out] INFO
+*> \verbatim
+*> INFO is INTEGER
+*> = 0: successful exit
+*> < 0: if INFO = -k, the k-th argument had an illegal value
+*> > 0: if INFO = k, D(k,k) is exactly zero. The factorization
+*> has been completed, but the block diagonal matrix D is
+*> exactly singular, and division by zero will occur if it
+*> is used to solve a system of equations.
+*> \endverbatim
+*
+* Authors:
+* ========
+*
+*> \author Univ. of Tennessee
+*> \author Univ. of California Berkeley
+*> \author Univ. of Colorado Denver
+*> \author NAG Ltd.
+*
+*> \date December 2016
+*
+*> \ingroup complex16SYcomputational
+*
+*> \par Further Details:
+* =====================
+*>
+*> \verbatim
+*>
+*> If UPLO = 'U', then A = U*D*U**T, where
+*> U = P(n)*U(n)* ... *P(k)U(k)* ...,
+*> i.e., U is a product of terms P(k)*U(k), where k decreases from n to
+*> 1 in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1
+*> and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as
+*> defined by IPIV(k), and U(k) is a unit upper triangular matrix, such
+*> that if the diagonal block D(k) is of order s (s = 1 or 2), then
+*>
+*> ( I v 0 ) k-s
+*> U(k) = ( 0 I 0 ) s
+*> ( 0 0 I ) n-k
+*> k-s s n-k
+*>
+*> If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k-1,k).
+*> If s = 2, the upper triangle of D(k) overwrites A(k-1,k-1), A(k-1,k),
+*> and A(k,k), and v overwrites A(1:k-2,k-1:k).
+*>
+*> If UPLO = 'L', then A = L*D*L**T, where
+*> L = P(1)*L(1)* ... *P(k)*L(k)* ...,
+*> i.e., L is a product of terms P(k)*L(k), where k increases from 1 to
+*> n in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1
+*> and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as
+*> defined by IPIV(k), and L(k) is a unit lower triangular matrix, such
+*> that if the diagonal block D(k) is of order s (s = 1 or 2), then
+*>
+*> ( I 0 0 ) k-1
+*> L(k) = ( 0 I 0 ) s
+*> ( 0 v I ) n-k-s+1
+*> k-1 s n-k-s+1
+*>
+*> If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k).
+*> If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k),
+*> and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1).
+*> \endverbatim
+*
+*> \par Contributors:
+* ==================
+*>
+*> \verbatim
+*>
+*> 09-29-06 - patch from
+*> Bobby Cheng, MathWorks
+*>
+*> Replace l.209 and l.377
+*> IF( MAX( ABSAKK, COLMAX ).EQ.ZERO ) THEN
+*> by
+*> IF( (MAX( ABSAKK, COLMAX ).EQ.ZERO) .OR. DISNAN(ABSAKK) ) THEN
+*>
+*> 1-96 - Based on modifications by J. Lewis, Boeing Computer Services
+*> Company
+*> \endverbatim
+*
+* =====================================================================
SUBROUTINE ZSYTF2( UPLO, N, A, LDA, IPIV, INFO )
*
-* -- LAPACK routine (version 3.2) --
+* -- LAPACK computational routine (version 3.7.0) --
* -- LAPACK is a software package provided by Univ. of Tennessee, --
* -- Univ. of California Berkeley, Univ. of Colorado Denver and NAG Ltd..--
-* November 2006
+* December 2016
*
* .. Scalar Arguments ..
CHARACTER UPLO
@@ -14,113 +205,6 @@
COMPLEX*16 A( LDA, * )
* ..
*
-* Purpose
-* =======
-*
-* ZSYTF2 computes the factorization of a complex symmetric matrix A
-* using the Bunch-Kaufman diagonal pivoting method:
-*
-* A = U*D*U' or A = L*D*L'
-*
-* where U (or L) is a product of permutation and unit upper (lower)
-* triangular matrices, U' is the transpose of U, and D is symmetric and
-* block diagonal with 1-by-1 and 2-by-2 diagonal blocks.
-*
-* This is the unblocked version of the algorithm, calling Level 2 BLAS.
-*
-* Arguments
-* =========
-*
-* UPLO (input) CHARACTER*1
-* Specifies whether the upper or lower triangular part of the
-* symmetric matrix A is stored:
-* = 'U': Upper triangular
-* = 'L': Lower triangular
-*
-* N (input) INTEGER
-* The order of the matrix A. N >= 0.
-*
-* A (input/output) COMPLEX*16 array, dimension (LDA,N)
-* On entry, the symmetric matrix A. If UPLO = 'U', the leading
-* n-by-n upper triangular part of A contains the upper
-* triangular part of the matrix A, and the strictly lower
-* triangular part of A is not referenced. If UPLO = 'L', the
-* leading n-by-n lower triangular part of A contains the lower
-* triangular part of the matrix A, and the strictly upper
-* triangular part of A is not referenced.
-*
-* On exit, the block diagonal matrix D and the multipliers used
-* to obtain the factor U or L (see below for further details).
-*
-* LDA (input) INTEGER
-* The leading dimension of the array A. LDA >= max(1,N).
-*
-* IPIV (output) INTEGER array, dimension (N)
-* Details of the interchanges and the block structure of D.
-* If IPIV(k) > 0, then rows and columns k and IPIV(k) were
-* interchanged and D(k,k) is a 1-by-1 diagonal block.
-* If UPLO = 'U' and IPIV(k) = IPIV(k-1) < 0, then rows and
-* columns k-1 and -IPIV(k) were interchanged and D(k-1:k,k-1:k)
-* is a 2-by-2 diagonal block. If UPLO = 'L' and IPIV(k) =
-* IPIV(k+1) < 0, then rows and columns k+1 and -IPIV(k) were
-* interchanged and D(k:k+1,k:k+1) is a 2-by-2 diagonal block.
-*
-* INFO (output) INTEGER
-* = 0: successful exit
-* < 0: if INFO = -k, the k-th argument had an illegal value
-* > 0: if INFO = k, D(k,k) is exactly zero. The factorization
-* has been completed, but the block diagonal matrix D is
-* exactly singular, and division by zero will occur if it
-* is used to solve a system of equations.
-*
-* Further Details
-* ===============
-*
-* 09-29-06 - patch from
-* Bobby Cheng, MathWorks
-*
-* Replace l.209 and l.377
-* IF( MAX( ABSAKK, COLMAX ).EQ.ZERO ) THEN
-* by
-* IF( (MAX( ABSAKK, COLMAX ).EQ.ZERO) .OR. DISNAN(ABSAKK) ) THEN
-*
-* 1-96 - Based on modifications by J. Lewis, Boeing Computer Services
-* Company
-*
-* If UPLO = 'U', then A = U*D*U', where
-* U = P(n)*U(n)* ... *P(k)U(k)* ...,
-* i.e., U is a product of terms P(k)*U(k), where k decreases from n to
-* 1 in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1
-* and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as
-* defined by IPIV(k), and U(k) is a unit upper triangular matrix, such
-* that if the diagonal block D(k) is of order s (s = 1 or 2), then
-*
-* ( I v 0 ) k-s
-* U(k) = ( 0 I 0 ) s
-* ( 0 0 I ) n-k
-* k-s s n-k
-*
-* If s = 1, D(k) overwrites A(k,k), and v overwrites A(1:k-1,k).
-* If s = 2, the upper triangle of D(k) overwrites A(k-1,k-1), A(k-1,k),
-* and A(k,k), and v overwrites A(1:k-2,k-1:k).
-*
-* If UPLO = 'L', then A = L*D*L', where
-* L = P(1)*L(1)* ... *P(k)*L(k)* ...,
-* i.e., L is a product of terms P(k)*L(k), where k increases from 1 to
-* n in steps of 1 or 2, and D is a block diagonal matrix with 1-by-1
-* and 2-by-2 diagonal blocks D(k). P(k) is a permutation matrix as
-* defined by IPIV(k), and L(k) is a unit lower triangular matrix, such
-* that if the diagonal block D(k) is of order s (s = 1 or 2), then
-*
-* ( I 0 0 ) k-1
-* L(k) = ( 0 I 0 ) s
-* ( 0 v I ) n-k-s+1
-* k-1 s n-k-s+1
-*
-* If s = 1, D(k) overwrites A(k,k), and v overwrites A(k+1:n,k).
-* If s = 2, the lower triangle of D(k) overwrites A(k,k), A(k+1,k),
-* and A(k+1,k+1), and v overwrites A(k+2:n,k:k+1).
-*
* =====================================================================
*
* .. Parameters ..
@@ -178,7 +262,7 @@
*
IF( UPPER ) THEN
*
-* Factorize A as U*D*U' using the upper triangle of A
+* Factorize A as U*D*U**T using the upper triangle of A
*
* K is the main loop index, decreasing from N to 1 in steps of
* 1 or 2
@@ -198,7 +282,8 @@
ABSAKK = CABS1( A( K, K ) )
*
* IMAX is the row-index of the largest off-diagonal element in
-* column K, and COLMAX is its absolute value
+* column K, and COLMAX is its absolute value.
+* Determine both COLMAX and IMAX.
*
IF( K.GT.1 ) THEN
IMAX = IZAMAX( K-1, A( 1, K ), 1 )
@@ -209,7 +294,8 @@
*
IF( MAX( ABSAKK, COLMAX ).EQ.ZERO .OR. DISNAN(ABSAKK) ) THEN
*
-* Column K is zero or contains a NaN: set INFO and continue
+* Column K is zero or underflow, or contains a NaN:
+* set INFO and continue
*
IF( INFO.EQ.0 )
$ INFO = K
@@ -284,7 +370,7 @@
*
* Perform a rank-1 update of A(1:k-1,1:k-1) as
*
-* A := A - U(k)*D(k)*U(k)' = A - W(k)*1/D(k)*W(k)'
+* A := A - U(k)*D(k)*U(k)**T = A - W(k)*1/D(k)*W(k)**T
*
R1 = CONE / A( K, K )
CALL ZSYR( UPLO, K-1, -R1, A( 1, K ), 1, A, LDA )
@@ -303,8 +389,8 @@
*
* Perform a rank-2 update of A(1:k-2,1:k-2) as
*
-* A := A - ( U(k-1) U(k) )*D(k)*( U(k-1) U(k) )'
-* = A - ( W(k-1) W(k) )*inv(D(k))*( W(k-1) W(k) )'
+* A := A - ( U(k-1) U(k) )*D(k)*( U(k-1) U(k) )**T
+* = A - ( W(k-1) W(k) )*inv(D(k))*( W(k-1) W(k) )**T
*
IF( K.GT.2 ) THEN
*
@@ -346,7 +432,7 @@
*
ELSE
*
-* Factorize A as L*D*L' using the lower triangle of A
+* Factorize A as L*D*L**T using the lower triangle of A
*
* K is the main loop index, increasing from 1 to N in steps of
* 1 or 2
@@ -366,7 +452,8 @@
ABSAKK = CABS1( A( K, K ) )
*
* IMAX is the row-index of the largest off-diagonal element in
-* column K, and COLMAX is its absolute value
+* column K, and COLMAX is its absolute value.
+* Determine both COLMAX and IMAX.
*
IF( K.LT.N ) THEN
IMAX = K + IZAMAX( N-K, A( K+1, K ), 1 )
@@ -377,7 +464,8 @@
*
IF( MAX( ABSAKK, COLMAX ).EQ.ZERO .OR. DISNAN(ABSAKK) ) THEN
*
-* Column K is zero or contains a NaN: set INFO and continue
+* Column K is zero or underflow, or contains a NaN:
+* set INFO and continue
*
IF( INFO.EQ.0 )
$ INFO = K
@@ -455,7 +543,7 @@
*
* Perform a rank-1 update of A(k+1:n,k+1:n) as
*
-* A := A - L(k)*D(k)*L(k)' = A - W(k)*(1/D(k))*W(k)'
+* A := A - L(k)*D(k)*L(k)**T = A - W(k)*(1/D(k))*W(k)**T
*
R1 = CONE / A( K, K )
CALL ZSYR( UPLO, N-K, -R1, A( K+1, K ), 1,
@@ -473,8 +561,8 @@
*
* Perform a rank-2 update of A(k+2:n,k+2:n) as
*
-* A := A - ( L(k) L(k+1) )*D(k)*( L(k) L(k+1) )'
-* = A - ( W(k) W(k+1) )*inv(D(k))*( W(k) W(k+1) )'
+* A := A - ( L(k) L(k+1) )*D(k)*( L(k) L(k+1) )**T
+* = A - ( W(k) W(k+1) )*inv(D(k))*( W(k) W(k+1) )**T
*
* where L(k) and L(k+1) are the k-th and (k+1)-th
* columns of L