Purpose
To solve the overdetermined or underdetermined real linear systems
involving an M*K-by-N*L block Toeplitz matrix T that is specified
by its first block column and row. It is assumed that T has full
rank.
The following options are provided:
1. If JOB = 'O' or JOB = 'A' : find the least squares solution of
an overdetermined system, i.e., solve the least squares problem
minimize || B - T*X ||. (1)
2. If JOB = 'U' or JOB = 'A' : find the minimum norm solution of
the undetermined system
T
T * X = C. (2)
Specification
SUBROUTINE MB02ID( JOB, K, L, M, N, RB, RC, TC, LDTC, TR, LDTR, B,
$ LDB, C, LDC, DWORK, LDWORK, INFO )
C .. Scalar Arguments ..
CHARACTER JOB
INTEGER INFO, K, L, LDB, LDC, LDTC, LDTR, LDWORK, M, N,
$ RB, RC
C .. Array Arguments ..
DOUBLE PRECISION B(LDB,*), C(LDC,*), DWORK(LDWORK), TC(LDTC,*),
$ TR(LDTR,*)
Arguments
Mode Parameters
JOB CHARACTER*1
Specifies the problem to be solved as follows
= 'O': solve the overdetermined system (1);
= 'U': solve the underdetermined system (2);
= 'A': solve (1) and (2).
Input/Output Parameters
K (input) INTEGER
The number of rows in the blocks of T. K >= 0.
L (input) INTEGER
The number of columns in the blocks of T. L >= 0.
M (input) INTEGER
The number of blocks in the first block column of T.
M >= 0.
N (input) INTEGER
The number of blocks in the first block row of T.
0 <= N <= M*K / L.
RB (input) INTEGER
If JOB = 'O' or 'A', the number of columns in B. RB >= 0.
RC (input) INTEGER
If JOB = 'U' or 'A', the number of columns in C. RC >= 0.
TC (input) DOUBLE PRECISION array, dimension (LDTC,L)
On entry, the leading M*K-by-L part of this array must
contain the first block column of T.
LDTC INTEGER
The leading dimension of the array TC. LDTC >= MAX(1,M*K)
TR (input) DOUBLE PRECISION array, dimension (LDTR,(N-1)*L)
On entry, the leading K-by-(N-1)*L part of this array must
contain the 2nd to the N-th blocks of the first block row
of T.
LDTR INTEGER
The leading dimension of the array TR. LDTR >= MAX(1,K).
B (input/output) DOUBLE PRECISION array, dimension (LDB,RB)
On entry, if JOB = 'O' or JOB = 'A', the leading M*K-by-RB
part of this array must contain the right hand side
matrix B of the overdetermined system (1).
On exit, if JOB = 'O' or JOB = 'A', the leading N*L-by-RB
part of this array contains the solution of the
overdetermined system (1).
This array is not referenced if JOB = 'U'.
LDB INTEGER
The leading dimension of the array B.
LDB >= MAX(1,M*K), if JOB = 'O' or JOB = 'A';
LDB >= 1, if JOB = 'U'.
C (input) DOUBLE PRECISION array, dimension (LDC,RC)
On entry, if JOB = 'U' or JOB = 'A', the leading N*L-by-RC
part of this array must contain the right hand side
matrix C of the underdetermined system (2).
On exit, if JOB = 'U' or JOB = 'A', the leading M*K-by-RC
part of this array contains the solution of the
underdetermined system (2).
This array is not referenced if JOB = 'O'.
LDC INTEGER
The leading dimension of the array C.
LDB >= 1, if JOB = 'O';
LDB >= MAX(1,M*K), if JOB = 'U' or JOB = 'A'.
Workspace
DWORK DOUBLE PRECISION array, dimension (LDWORK)
On exit, if INFO = 0, DWORK(1) returns the optimal
value of LDWORK.
On exit, if INFO = -17, DWORK(1) returns the minimum
value of LDWORK.
LDWORK INTEGER
The length of the array DWORK.
Let x = MAX( 2*N*L*(L+K) + (6+N)*L,(N*L+M*K+1)*L + M*K )
and y = N*M*K*L + N*L, then
if MIN( M,N ) = 1 and JOB = 'O',
LDWORK >= MAX( y + MAX( M*K,RB ),1 );
if MIN( M,N ) = 1 and JOB = 'U',
LDWORK >= MAX( y + MAX( M*K,RC ),1 );
if MIN( M,N ) = 1 and JOB = 'A',
LDWORK >= MAX( y +MAX( M*K,MAX( RB,RC ),1 );
if MIN( M,N ) > 1 and JOB = 'O',
LDWORK >= MAX( x,N*L*RB + 1 );
if MIN( M,N ) > 1 and JOB = 'U',
LDWORK >= MAX( x,N*L*RC + 1 );
if MIN( M,N ) > 1 and JOB = 'A',
LDWORK >= MAX( x,N*L*MAX( RB,RC ) + 1 ).
For optimum performance LDWORK should be larger.
Error Indicator
INFO INTEGER
= 0: successful exit;
< 0: if INFO = -i, the i-th argument had an illegal
value;
= 1: the reduction algorithm failed. The Toeplitz matrix
associated with T is (numerically) not of full rank.
Method
Householder transformations and modified hyperbolic rotations are used in the Schur algorithm [1], [2].References
[1] Kailath, T. and Sayed, A.
Fast Reliable Algorithms for Matrices with Structure.
SIAM Publications, Philadelphia, 1999.
[2] Kressner, D. and Van Dooren, P.
Factorizations and linear system solvers for matrices with
Toeplitz structure.
SLICOT Working Note 2000-2, 2000.
Numerical Aspects
The algorithm requires O( L*L*K*(N+M)*log(N+M) + N*N*L*L*(L+K) )
and additionally
if JOB = 'O' or JOB = 'A',
O( (K*L+RB*L+K*RB)*(N+M)*log(N+M) + N*N*L*L*RB );
if JOB = 'U' or JOB = 'A',
O( (K*L+RC*L+K*RC)*(N+M)*log(N+M) + N*N*L*L*RC );
floating point operations.
Further Comments
NoneExample
Program Text
* MB02ID EXAMPLE PROGRAM TEXT
* Copyright (c) 2002-2010 NICONET e.V.
*
* .. Parameters ..
INTEGER NIN, NOUT
PARAMETER ( NIN = 5, NOUT = 6 )
INTEGER KMAX, LMAX, MMAX, NMAX, RBMAX, RCMAX
PARAMETER ( KMAX = 20, LMAX = 20, MMAX = 20, NMAX = 20,
$ RBMAX = 20, RCMAX = 20 )
INTEGER LDB, LDC, LDTC, LDTR, LDWORK
PARAMETER ( LDB = KMAX*MMAX, LDC = KMAX*MMAX,
$ LDTC = MMAX*KMAX, LDTR = KMAX,
$ LDWORK = 2*NMAX*LMAX*( LMAX + KMAX ) +
$ ( 6 + NMAX )*LMAX +
$ MMAX*KMAX*( LMAX + 1 ) +
$ RBMAX + RCMAX )
* .. Local Scalars ..
INTEGER I, INFO, J, K, L, M, N, RB, RC
CHARACTER JOB
DOUBLE PRECISION B(LDB,RBMAX), C(LDC,RCMAX), DWORK(LDWORK),
$ TC(LDTC,LMAX), TR(LDTR,NMAX*LMAX)
* .. External Functions ..
LOGICAL LSAME
EXTERNAL LSAME
* .. External Subroutines ..
EXTERNAL MB02ID
*
* .. Executable Statements ..
WRITE ( NOUT, FMT = 99999 )
* Skip the heading in the data file and read the data.
READ ( NIN, FMT = '()' )
READ ( NIN, FMT = * ) K, L, M, N, RB, RC, JOB
IF( K.LE.0 .OR. K.GT.KMAX ) THEN
WRITE ( NOUT, FMT = 99994 ) K
ELSE IF( L.LE.0 .OR. L.GT.LMAX ) THEN
WRITE ( NOUT, FMT = 99993 ) L
ELSE IF( M.LE.0 .OR. M.GT.MMAX ) THEN
WRITE ( NOUT, FMT = 99992 ) M
ELSE IF( N.LE.0 .OR. N.GT.NMAX ) THEN
WRITE ( NOUT, FMT = 99991 ) N
ELSE IF ( ( LSAME( JOB, 'O' ) .OR. LSAME( JOB, 'A' ) )
$ .AND. ( ( RB.LE.0 ) .OR. ( RB.GT.RBMAX ) ) ) THEN
WRITE ( NOUT, FMT = 99990 ) RB
ELSE IF ( ( LSAME( JOB, 'U' ) .OR. LSAME( JOB, 'A' ) )
$ .AND. ( ( RC.LE.0 ) .OR. ( RC.GT.RCMAX ) ) ) THEN
WRITE ( NOUT, FMT = 99989 ) RC
ELSE
READ ( NIN, FMT = * ) ( ( TC(I,J), J = 1,L ), I = 1,M*K )
READ ( NIN, FMT = * ) ( ( TR(I,J), J = 1,(N-1)*L ), I = 1,K )
IF ( LSAME( JOB, 'O' ) .OR. LSAME( JOB, 'A' ) ) THEN
READ ( NIN, FMT = * ) ( ( B(I,J), J = 1,RB ), I = 1,M*K )
END IF
IF ( LSAME( JOB, 'U' ) .OR. LSAME( JOB, 'A' ) ) THEN
READ ( NIN, FMT = * ) ( ( C(I,J), J = 1,RC ), I = 1,N*L )
END IF
CALL MB02ID( JOB, K, L, M, N, RB, RC, TC, LDTC, TR, LDTR, B,
$ LDB, C, LDC, DWORK, LDWORK, INFO )
IF ( INFO.NE.0 ) THEN
WRITE ( NOUT, FMT = 99998 ) INFO
ELSE
IF ( LSAME( JOB, 'O' ) .OR. LSAME( JOB, 'A' ) ) THEN
WRITE ( NOUT, FMT = 99997 )
DO 10 I = 1, N*L
WRITE ( NOUT, FMT = 99995 ) ( B(I,J), J = 1, RB )
10 CONTINUE
END IF
IF ( LSAME( JOB, 'U' ) .OR. LSAME( JOB, 'A' ) ) THEN
WRITE ( NOUT, FMT = 99996 )
DO 20 I = 1, M*K
WRITE ( NOUT, FMT = 99995 ) ( C(I,J), J = 1, RC )
20 CONTINUE
END IF
END IF
END IF
STOP
*
99999 FORMAT (' MB02ID EXAMPLE PROGRAM RESULTS',/1X)
99998 FORMAT (' INFO on exit from MB02ID = ',I2)
99997 FORMAT (' The least squares solution of T * X = B is ')
99996 FORMAT (' The minimum norm solution of T^T * X = C is ')
99995 FORMAT (20(1X,F8.4))
99994 FORMAT (/' K is out of range.',/' K = ',I5)
99993 FORMAT (/' L is out of range.',/' L = ',I5)
99992 FORMAT (/' M is out of range.',/' M = ',I5)
99991 FORMAT (/' N is out of range.',/' N = ',I5)
99990 FORMAT (/' RB is out of range.',/' RB = ',I5)
99989 FORMAT (/' RC is out of range.',/' RC = ',I5)
END
Program Data
MB02ID EXAMPLE PROGRAM DATA
3 2 4 3 1 1 A
5.0 2.0
1.0 2.0
4.0 3.0
4.0 0.0
2.0 2.0
3.0 3.0
5.0 1.0
3.0 3.0
1.0 1.0
2.0 3.0
1.0 3.0
2.0 2.0
1.0 4.0 2.0 3.0
2.0 2.0 2.0 4.0
3.0 1.0 0.0 1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
1.0
Program Results
MB02ID EXAMPLE PROGRAM RESULTS The least squares solution of T * X = B is 0.0379 0.1677 0.0485 -0.0038 0.0429 0.1365 The minimum norm solution of T^T * X = C is 0.0509 0.0547 0.0218 0.0008 0.0436 0.0404 0.0031 0.0451 0.0421 0.0243 0.0556 0.0472
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