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diff --git a/src/fortran/lapack/dtgevc.f b/src/fortran/lapack/dtgevc.f new file mode 100644 index 0000000..091c3f6 --- /dev/null +++ b/src/fortran/lapack/dtgevc.f @@ -0,0 +1,1147 @@ + SUBROUTINE DTGEVC( SIDE, HOWMNY, SELECT, N, S, LDS, P, LDP, VL, + $ LDVL, VR, LDVR, MM, M, WORK, INFO ) +* +* -- LAPACK routine (version 3.1) -- +* Univ. of Tennessee, Univ. of California Berkeley and NAG Ltd.. +* November 2006 +* +* .. Scalar Arguments .. + CHARACTER HOWMNY, SIDE + INTEGER INFO, LDP, LDS, LDVL, LDVR, M, MM, N +* .. +* .. Array Arguments .. + LOGICAL SELECT( * ) + DOUBLE PRECISION P( LDP, * ), S( LDS, * ), VL( LDVL, * ), + $ VR( LDVR, * ), WORK( * ) +* .. +* +* +* Purpose +* ======= +* +* DTGEVC computes some or all of the right and/or left eigenvectors of +* a pair of real matrices (S,P), where S is a quasi-triangular matrix +* and P is upper triangular. Matrix pairs of this type are produced by +* the generalized Schur factorization of a matrix pair (A,B): +* +* A = Q*S*Z**T, B = Q*P*Z**T +* +* as computed by DGGHRD + DHGEQZ. +* +* The right eigenvector x and the left eigenvector y of (S,P) +* corresponding to an eigenvalue w are defined by: +* +* S*x = w*P*x, (y**H)*S = w*(y**H)*P, +* +* where y**H denotes the conjugate tranpose of y. +* The eigenvalues are not input to this routine, but are computed +* directly from the diagonal blocks of S and P. +* +* This routine returns the matrices X and/or Y of right and left +* eigenvectors of (S,P), or the products Z*X and/or Q*Y, +* where Z and Q are input matrices. +* If Q and Z are the orthogonal factors from the generalized Schur +* factorization of a matrix pair (A,B), then Z*X and Q*Y +* are the matrices of right and left eigenvectors of (A,B). +* +* Arguments +* ========= +* +* SIDE (input) CHARACTER*1 +* = 'R': compute right eigenvectors only; +* = 'L': compute left eigenvectors only; +* = 'B': compute both right and left eigenvectors. +* +* HOWMNY (input) CHARACTER*1 +* = 'A': compute all right and/or left eigenvectors; +* = 'B': compute all right and/or left eigenvectors, +* backtransformed by the matrices in VR and/or VL; +* = 'S': compute selected right and/or left eigenvectors, +* specified by the logical array SELECT. +* +* SELECT (input) LOGICAL array, dimension (N) +* If HOWMNY='S', SELECT specifies the eigenvectors to be +* computed. If w(j) is a real eigenvalue, the corresponding +* real eigenvector is computed if SELECT(j) is .TRUE.. +* If w(j) and w(j+1) are the real and imaginary parts of a +* complex eigenvalue, the corresponding complex eigenvector +* is computed if either SELECT(j) or SELECT(j+1) is .TRUE., +* and on exit SELECT(j) is set to .TRUE. and SELECT(j+1) is +* set to .FALSE.. +* Not referenced if HOWMNY = 'A' or 'B'. +* +* N (input) INTEGER +* The order of the matrices S and P. N >= 0. +* +* S (input) DOUBLE PRECISION array, dimension (LDS,N) +* The upper quasi-triangular matrix S from a generalized Schur +* factorization, as computed by DHGEQZ. +* +* LDS (input) INTEGER +* The leading dimension of array S. LDS >= max(1,N). +* +* P (input) DOUBLE PRECISION array, dimension (LDP,N) +* The upper triangular matrix P from a generalized Schur +* factorization, as computed by DHGEQZ. +* 2-by-2 diagonal blocks of P corresponding to 2-by-2 blocks +* of S must be in positive diagonal form. +* +* LDP (input) INTEGER +* The leading dimension of array P. LDP >= max(1,N). +* +* VL (input/output) DOUBLE PRECISION array, dimension (LDVL,MM) +* On entry, if SIDE = 'L' or 'B' and HOWMNY = 'B', VL must +* contain an N-by-N matrix Q (usually the orthogonal matrix Q +* of left Schur vectors returned by DHGEQZ). +* On exit, if SIDE = 'L' or 'B', VL contains: +* if HOWMNY = 'A', the matrix Y of left eigenvectors of (S,P); +* if HOWMNY = 'B', the matrix Q*Y; +* if HOWMNY = 'S', the left eigenvectors of (S,P) specified by +* SELECT, stored consecutively in the columns of +* VL, in the same order as their eigenvalues. +* +* A complex eigenvector corresponding to a complex eigenvalue +* is stored in two consecutive columns, the first holding the +* real part, and the second the imaginary part. +* +* Not referenced if SIDE = 'R'. +* +* LDVL (input) INTEGER +* The leading dimension of array VL. LDVL >= 1, and if +* SIDE = 'L' or 'B', LDVL >= N. +* +* VR (input/output) DOUBLE PRECISION array, dimension (LDVR,MM) +* On entry, if SIDE = 'R' or 'B' and HOWMNY = 'B', VR must +* contain an N-by-N matrix Z (usually the orthogonal matrix Z +* of right Schur vectors returned by DHGEQZ). +* +* On exit, if SIDE = 'R' or 'B', VR contains: +* if HOWMNY = 'A', the matrix X of right eigenvectors of (S,P); +* if HOWMNY = 'B' or 'b', the matrix Z*X; +* if HOWMNY = 'S' or 's', the right eigenvectors of (S,P) +* specified by SELECT, stored consecutively in the +* columns of VR, in the same order as their +* eigenvalues. +* +* A complex eigenvector corresponding to a complex eigenvalue +* is stored in two consecutive columns, the first holding the +* real part and the second the imaginary part. +* +* Not referenced if SIDE = 'L'. +* +* LDVR (input) INTEGER +* The leading dimension of the array VR. LDVR >= 1, and if +* SIDE = 'R' or 'B', LDVR >= N. +* +* MM (input) INTEGER +* The number of columns in the arrays VL and/or VR. MM >= M. +* +* M (output) INTEGER +* The number of columns in the arrays VL and/or VR actually +* used to store the eigenvectors. If HOWMNY = 'A' or 'B', M +* is set to N. Each selected real eigenvector occupies one +* column and each selected complex eigenvector occupies two +* columns. +* +* WORK (workspace) DOUBLE PRECISION array, dimension (6*N) +* +* INFO (output) INTEGER +* = 0: successful exit. +* < 0: if INFO = -i, the i-th argument had an illegal value. +* > 0: the 2-by-2 block (INFO:INFO+1) does not have a complex +* eigenvalue. +* +* Further Details +* =============== +* +* Allocation of workspace: +* ---------- -- --------- +* +* WORK( j ) = 1-norm of j-th column of A, above the diagonal +* WORK( N+j ) = 1-norm of j-th column of B, above the diagonal +* WORK( 2*N+1:3*N ) = real part of eigenvector +* WORK( 3*N+1:4*N ) = imaginary part of eigenvector +* WORK( 4*N+1:5*N ) = real part of back-transformed eigenvector +* WORK( 5*N+1:6*N ) = imaginary part of back-transformed eigenvector +* +* Rowwise vs. columnwise solution methods: +* ------- -- ---------- -------- ------- +* +* Finding a generalized eigenvector consists basically of solving the +* singular triangular system +* +* (A - w B) x = 0 (for right) or: (A - w B)**H y = 0 (for left) +* +* Consider finding the i-th right eigenvector (assume all eigenvalues +* are real). The equation to be solved is: +* n i +* 0 = sum C(j,k) v(k) = sum C(j,k) v(k) for j = i,. . .,1 +* k=j k=j +* +* where C = (A - w B) (The components v(i+1:n) are 0.) +* +* The "rowwise" method is: +* +* (1) v(i) := 1 +* for j = i-1,. . .,1: +* i +* (2) compute s = - sum C(j,k) v(k) and +* k=j+1 +* +* (3) v(j) := s / C(j,j) +* +* Step 2 is sometimes called the "dot product" step, since it is an +* inner product between the j-th row and the portion of the eigenvector +* that has been computed so far. +* +* The "columnwise" method consists basically in doing the sums +* for all the rows in parallel. As each v(j) is computed, the +* contribution of v(j) times the j-th column of C is added to the +* partial sums. Since FORTRAN arrays are stored columnwise, this has +* the advantage that at each step, the elements of C that are accessed +* are adjacent to one another, whereas with the rowwise method, the +* elements accessed at a step are spaced LDS (and LDP) words apart. +* +* When finding left eigenvectors, the matrix in question is the +* transpose of the one in storage, so the rowwise method then +* actually accesses columns of A and B at each step, and so is the +* preferred method. +* +* ===================================================================== +* +* .. Parameters .. + DOUBLE PRECISION ZERO, ONE, SAFETY + PARAMETER ( ZERO = 0.0D+0, ONE = 1.0D+0, + $ SAFETY = 1.0D+2 ) +* .. +* .. Local Scalars .. + LOGICAL COMPL, COMPR, IL2BY2, ILABAD, ILALL, ILBACK, + $ ILBBAD, ILCOMP, ILCPLX, LSA, LSB + INTEGER I, IBEG, IEIG, IEND, IHWMNY, IINFO, IM, ISIDE, + $ J, JA, JC, JE, JR, JW, NA, NW + DOUBLE PRECISION ACOEF, ACOEFA, ANORM, ASCALE, BCOEFA, BCOEFI, + $ BCOEFR, BIG, BIGNUM, BNORM, BSCALE, CIM2A, + $ CIM2B, CIMAGA, CIMAGB, CRE2A, CRE2B, CREALA, + $ CREALB, DMIN, SAFMIN, SALFAR, SBETA, SCALE, + $ SMALL, TEMP, TEMP2, TEMP2I, TEMP2R, ULP, XMAX, + $ XSCALE +* .. +* .. Local Arrays .. + DOUBLE PRECISION BDIAG( 2 ), SUM( 2, 2 ), SUMS( 2, 2 ), + $ SUMP( 2, 2 ) +* .. +* .. External Functions .. + LOGICAL LSAME + DOUBLE PRECISION DLAMCH + EXTERNAL LSAME, DLAMCH +* .. +* .. External Subroutines .. + EXTERNAL DGEMV, DLABAD, DLACPY, DLAG2, DLALN2, XERBLA +* .. +* .. Intrinsic Functions .. + INTRINSIC ABS, MAX, MIN +* .. +* .. Executable Statements .. +* +* Decode and Test the input parameters +* + IF( LSAME( HOWMNY, 'A' ) ) THEN + IHWMNY = 1 + ILALL = .TRUE. + ILBACK = .FALSE. + ELSE IF( LSAME( HOWMNY, 'S' ) ) THEN + IHWMNY = 2 + ILALL = .FALSE. + ILBACK = .FALSE. + ELSE IF( LSAME( HOWMNY, 'B' ) ) THEN + IHWMNY = 3 + ILALL = .TRUE. + ILBACK = .TRUE. + ELSE + IHWMNY = -1 + ILALL = .TRUE. + END IF +* + IF( LSAME( SIDE, 'R' ) ) THEN + ISIDE = 1 + COMPL = .FALSE. + COMPR = .TRUE. + ELSE IF( LSAME( SIDE, 'L' ) ) THEN + ISIDE = 2 + COMPL = .TRUE. + COMPR = .FALSE. + ELSE IF( LSAME( SIDE, 'B' ) ) THEN + ISIDE = 3 + COMPL = .TRUE. + COMPR = .TRUE. + ELSE + ISIDE = -1 + END IF +* + INFO = 0 + IF( ISIDE.LT.0 ) THEN + INFO = -1 + ELSE IF( IHWMNY.LT.0 ) THEN + INFO = -2 + ELSE IF( N.LT.0 ) THEN + INFO = -4 + ELSE IF( LDS.LT.MAX( 1, N ) ) THEN + INFO = -6 + ELSE IF( LDP.LT.MAX( 1, N ) ) THEN + INFO = -8 + END IF + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'DTGEVC', -INFO ) + RETURN + END IF +* +* Count the number of eigenvectors to be computed +* + IF( .NOT.ILALL ) THEN + IM = 0 + ILCPLX = .FALSE. + DO 10 J = 1, N + IF( ILCPLX ) THEN + ILCPLX = .FALSE. + GO TO 10 + END IF + IF( J.LT.N ) THEN + IF( S( J+1, J ).NE.ZERO ) + $ ILCPLX = .TRUE. + END IF + IF( ILCPLX ) THEN + IF( SELECT( J ) .OR. SELECT( J+1 ) ) + $ IM = IM + 2 + ELSE + IF( SELECT( J ) ) + $ IM = IM + 1 + END IF + 10 CONTINUE + ELSE + IM = N + END IF +* +* Check 2-by-2 diagonal blocks of A, B +* + ILABAD = .FALSE. + ILBBAD = .FALSE. + DO 20 J = 1, N - 1 + IF( S( J+1, J ).NE.ZERO ) THEN + IF( P( J, J ).EQ.ZERO .OR. P( J+1, J+1 ).EQ.ZERO .OR. + $ P( J, J+1 ).NE.ZERO )ILBBAD = .TRUE. + IF( J.LT.N-1 ) THEN + IF( S( J+2, J+1 ).NE.ZERO ) + $ ILABAD = .TRUE. + END IF + END IF + 20 CONTINUE +* + IF( ILABAD ) THEN + INFO = -5 + ELSE IF( ILBBAD ) THEN + INFO = -7 + ELSE IF( COMPL .AND. LDVL.LT.N .OR. LDVL.LT.1 ) THEN + INFO = -10 + ELSE IF( COMPR .AND. LDVR.LT.N .OR. LDVR.LT.1 ) THEN + INFO = -12 + ELSE IF( MM.LT.IM ) THEN + INFO = -13 + END IF + IF( INFO.NE.0 ) THEN + CALL XERBLA( 'DTGEVC', -INFO ) + RETURN + END IF +* +* Quick return if possible +* + M = IM + IF( N.EQ.0 ) + $ RETURN +* +* Machine Constants +* + SAFMIN = DLAMCH( 'Safe minimum' ) + BIG = ONE / SAFMIN + CALL DLABAD( SAFMIN, BIG ) + ULP = DLAMCH( 'Epsilon' )*DLAMCH( 'Base' ) + SMALL = SAFMIN*N / ULP + BIG = ONE / SMALL + BIGNUM = ONE / ( SAFMIN*N ) +* +* Compute the 1-norm of each column of the strictly upper triangular +* part (i.e., excluding all elements belonging to the diagonal +* blocks) of A and B to check for possible overflow in the +* triangular solver. +* + ANORM = ABS( S( 1, 1 ) ) + IF( N.GT.1 ) + $ ANORM = ANORM + ABS( S( 2, 1 ) ) + BNORM = ABS( P( 1, 1 ) ) + WORK( 1 ) = ZERO + WORK( N+1 ) = ZERO +* + DO 50 J = 2, N + TEMP = ZERO + TEMP2 = ZERO + IF( S( J, J-1 ).EQ.ZERO ) THEN + IEND = J - 1 + ELSE + IEND = J - 2 + END IF + DO 30 I = 1, IEND + TEMP = TEMP + ABS( S( I, J ) ) + TEMP2 = TEMP2 + ABS( P( I, J ) ) + 30 CONTINUE + WORK( J ) = TEMP + WORK( N+J ) = TEMP2 + DO 40 I = IEND + 1, MIN( J+1, N ) + TEMP = TEMP + ABS( S( I, J ) ) + TEMP2 = TEMP2 + ABS( P( I, J ) ) + 40 CONTINUE + ANORM = MAX( ANORM, TEMP ) + BNORM = MAX( BNORM, TEMP2 ) + 50 CONTINUE +* + ASCALE = ONE / MAX( ANORM, SAFMIN ) + BSCALE = ONE / MAX( BNORM, SAFMIN ) +* +* Left eigenvectors +* + IF( COMPL ) THEN + IEIG = 0 +* +* Main loop over eigenvalues +* + ILCPLX = .FALSE. + DO 220 JE = 1, N +* +* Skip this iteration if (a) HOWMNY='S' and SELECT=.FALSE., or +* (b) this would be the second of a complex pair. +* Check for complex eigenvalue, so as to be sure of which +* entry(-ies) of SELECT to look at. +* + IF( ILCPLX ) THEN + ILCPLX = .FALSE. + GO TO 220 + END IF + NW = 1 + IF( JE.LT.N ) THEN + IF( S( JE+1, JE ).NE.ZERO ) THEN + ILCPLX = .TRUE. + NW = 2 + END IF + END IF + IF( ILALL ) THEN + ILCOMP = .TRUE. + ELSE IF( ILCPLX ) THEN + ILCOMP = SELECT( JE ) .OR. SELECT( JE+1 ) + ELSE + ILCOMP = SELECT( JE ) + END IF + IF( .NOT.ILCOMP ) + $ GO TO 220 +* +* Decide if (a) singular pencil, (b) real eigenvalue, or +* (c) complex eigenvalue. +* + IF( .NOT.ILCPLX ) THEN + IF( ABS( S( JE, JE ) ).LE.SAFMIN .AND. + $ ABS( P( JE, JE ) ).LE.SAFMIN ) THEN +* +* Singular matrix pencil -- return unit eigenvector +* + IEIG = IEIG + 1 + DO 60 JR = 1, N + VL( JR, IEIG ) = ZERO + 60 CONTINUE + VL( IEIG, IEIG ) = ONE + GO TO 220 + END IF + END IF +* +* Clear vector +* + DO 70 JR = 1, NW*N + WORK( 2*N+JR ) = ZERO + 70 CONTINUE +* T +* Compute coefficients in ( a A - b B ) y = 0 +* a is ACOEF +* b is BCOEFR + i*BCOEFI +* + IF( .NOT.ILCPLX ) THEN +* +* Real eigenvalue +* + TEMP = ONE / MAX( ABS( S( JE, JE ) )*ASCALE, + $ ABS( P( JE, JE ) )*BSCALE, SAFMIN ) + SALFAR = ( TEMP*S( JE, JE ) )*ASCALE + SBETA = ( TEMP*P( JE, JE ) )*BSCALE + ACOEF = SBETA*ASCALE + BCOEFR = SALFAR*BSCALE + BCOEFI = ZERO +* +* Scale to avoid underflow +* + SCALE = ONE + LSA = ABS( SBETA ).GE.SAFMIN .AND. ABS( ACOEF ).LT.SMALL + LSB = ABS( SALFAR ).GE.SAFMIN .AND. ABS( BCOEFR ).LT. + $ SMALL + IF( LSA ) + $ SCALE = ( SMALL / ABS( SBETA ) )*MIN( ANORM, BIG ) + IF( LSB ) + $ SCALE = MAX( SCALE, ( SMALL / ABS( SALFAR ) )* + $ MIN( BNORM, BIG ) ) + IF( LSA .OR. LSB ) THEN + SCALE = MIN( SCALE, ONE / + $ ( SAFMIN*MAX( ONE, ABS( ACOEF ), + $ ABS( BCOEFR ) ) ) ) + IF( LSA ) THEN + ACOEF = ASCALE*( SCALE*SBETA ) + ELSE + ACOEF = SCALE*ACOEF + END IF + IF( LSB ) THEN + BCOEFR = BSCALE*( SCALE*SALFAR ) + ELSE + BCOEFR = SCALE*BCOEFR + END IF + END IF + ACOEFA = ABS( ACOEF ) + BCOEFA = ABS( BCOEFR ) +* +* First component is 1 +* + WORK( 2*N+JE ) = ONE + XMAX = ONE + ELSE +* +* Complex eigenvalue +* + CALL DLAG2( S( JE, JE ), LDS, P( JE, JE ), LDP, + $ SAFMIN*SAFETY, ACOEF, TEMP, BCOEFR, TEMP2, + $ BCOEFI ) + BCOEFI = -BCOEFI + IF( BCOEFI.EQ.ZERO ) THEN + INFO = JE + RETURN + END IF +* +* Scale to avoid over/underflow +* + ACOEFA = ABS( ACOEF ) + BCOEFA = ABS( BCOEFR ) + ABS( BCOEFI ) + SCALE = ONE + IF( ACOEFA*ULP.LT.SAFMIN .AND. ACOEFA.GE.SAFMIN ) + $ SCALE = ( SAFMIN / ULP ) / ACOEFA + IF( BCOEFA*ULP.LT.SAFMIN .AND. BCOEFA.GE.SAFMIN ) + $ SCALE = MAX( SCALE, ( SAFMIN / ULP ) / BCOEFA ) + IF( SAFMIN*ACOEFA.GT.ASCALE ) + $ SCALE = ASCALE / ( SAFMIN*ACOEFA ) + IF( SAFMIN*BCOEFA.GT.BSCALE ) + $ SCALE = MIN( SCALE, BSCALE / ( SAFMIN*BCOEFA ) ) + IF( SCALE.NE.ONE ) THEN + ACOEF = SCALE*ACOEF + ACOEFA = ABS( ACOEF ) + BCOEFR = SCALE*BCOEFR + BCOEFI = SCALE*BCOEFI + BCOEFA = ABS( BCOEFR ) + ABS( BCOEFI ) + END IF +* +* Compute first two components of eigenvector +* + TEMP = ACOEF*S( JE+1, JE ) + TEMP2R = ACOEF*S( JE, JE ) - BCOEFR*P( JE, JE ) + TEMP2I = -BCOEFI*P( JE, JE ) + IF( ABS( TEMP ).GT.ABS( TEMP2R )+ABS( TEMP2I ) ) THEN + WORK( 2*N+JE ) = ONE + WORK( 3*N+JE ) = ZERO + WORK( 2*N+JE+1 ) = -TEMP2R / TEMP + WORK( 3*N+JE+1 ) = -TEMP2I / TEMP + ELSE + WORK( 2*N+JE+1 ) = ONE + WORK( 3*N+JE+1 ) = ZERO + TEMP = ACOEF*S( JE, JE+1 ) + WORK( 2*N+JE ) = ( BCOEFR*P( JE+1, JE+1 )-ACOEF* + $ S( JE+1, JE+1 ) ) / TEMP + WORK( 3*N+JE ) = BCOEFI*P( JE+1, JE+1 ) / TEMP + END IF + XMAX = MAX( ABS( WORK( 2*N+JE ) )+ABS( WORK( 3*N+JE ) ), + $ ABS( WORK( 2*N+JE+1 ) )+ABS( WORK( 3*N+JE+1 ) ) ) + END IF +* + DMIN = MAX( ULP*ACOEFA*ANORM, ULP*BCOEFA*BNORM, SAFMIN ) +* +* T +* Triangular solve of (a A - b B) y = 0 +* +* T +* (rowwise in (a A - b B) , or columnwise in (a A - b B) ) +* + IL2BY2 = .FALSE. +* + DO 160 J = JE + NW, N + IF( IL2BY2 ) THEN + IL2BY2 = .FALSE. + GO TO 160 + END IF +* + NA = 1 + BDIAG( 1 ) = P( J, J ) + IF( J.LT.N ) THEN + IF( S( J+1, J ).NE.ZERO ) THEN + IL2BY2 = .TRUE. + BDIAG( 2 ) = P( J+1, J+1 ) + NA = 2 + END IF + END IF +* +* Check whether scaling is necessary for dot products +* + XSCALE = ONE / MAX( ONE, XMAX ) + TEMP = MAX( WORK( J ), WORK( N+J ), + $ ACOEFA*WORK( J )+BCOEFA*WORK( N+J ) ) + IF( IL2BY2 ) + $ TEMP = MAX( TEMP, WORK( J+1 ), WORK( N+J+1 ), + $ ACOEFA*WORK( J+1 )+BCOEFA*WORK( N+J+1 ) ) + IF( TEMP.GT.BIGNUM*XSCALE ) THEN + DO 90 JW = 0, NW - 1 + DO 80 JR = JE, J - 1 + WORK( ( JW+2 )*N+JR ) = XSCALE* + $ WORK( ( JW+2 )*N+JR ) + 80 CONTINUE + 90 CONTINUE + XMAX = XMAX*XSCALE + END IF +* +* Compute dot products +* +* j-1 +* SUM = sum conjg( a*S(k,j) - b*P(k,j) )*x(k) +* k=je +* +* To reduce the op count, this is done as +* +* _ j-1 _ j-1 +* a*conjg( sum S(k,j)*x(k) ) - b*conjg( sum P(k,j)*x(k) ) +* k=je k=je +* +* which may cause underflow problems if A or B are close +* to underflow. (E.g., less than SMALL.) +* +* +* A series of compiler directives to defeat vectorization +* for the next loop +* +*$PL$ CMCHAR=' ' +CDIR$ NEXTSCALAR +C$DIR SCALAR +CDIR$ NEXT SCALAR +CVD$L NOVECTOR +CDEC$ NOVECTOR +CVD$ NOVECTOR +*VDIR NOVECTOR +*VOCL LOOP,SCALAR +CIBM PREFER SCALAR +*$PL$ CMCHAR='*' +* + DO 120 JW = 1, NW +* +*$PL$ CMCHAR=' ' +CDIR$ NEXTSCALAR +C$DIR SCALAR +CDIR$ NEXT SCALAR +CVD$L NOVECTOR +CDEC$ NOVECTOR +CVD$ NOVECTOR +*VDIR NOVECTOR +*VOCL LOOP,SCALAR +CIBM PREFER SCALAR +*$PL$ CMCHAR='*' +* + DO 110 JA = 1, NA + SUMS( JA, JW ) = ZERO + SUMP( JA, JW ) = ZERO +* + DO 100 JR = JE, J - 1 + SUMS( JA, JW ) = SUMS( JA, JW ) + + $ S( JR, J+JA-1 )* + $ WORK( ( JW+1 )*N+JR ) + SUMP( JA, JW ) = SUMP( JA, JW ) + + $ P( JR, J+JA-1 )* + $ WORK( ( JW+1 )*N+JR ) + 100 CONTINUE + 110 CONTINUE + 120 CONTINUE +* +*$PL$ CMCHAR=' ' +CDIR$ NEXTSCALAR +C$DIR SCALAR +CDIR$ NEXT SCALAR +CVD$L NOVECTOR +CDEC$ NOVECTOR +CVD$ NOVECTOR +*VDIR NOVECTOR +*VOCL LOOP,SCALAR +CIBM PREFER SCALAR +*$PL$ CMCHAR='*' +* + DO 130 JA = 1, NA + IF( ILCPLX ) THEN + SUM( JA, 1 ) = -ACOEF*SUMS( JA, 1 ) + + $ BCOEFR*SUMP( JA, 1 ) - + $ BCOEFI*SUMP( JA, 2 ) + SUM( JA, 2 ) = -ACOEF*SUMS( JA, 2 ) + + $ BCOEFR*SUMP( JA, 2 ) + + $ BCOEFI*SUMP( JA, 1 ) + ELSE + SUM( JA, 1 ) = -ACOEF*SUMS( JA, 1 ) + + $ BCOEFR*SUMP( JA, 1 ) + END IF + 130 CONTINUE +* +* T +* Solve ( a A - b B ) y = SUM(,) +* with scaling and perturbation of the denominator +* + CALL DLALN2( .TRUE., NA, NW, DMIN, ACOEF, S( J, J ), LDS, + $ BDIAG( 1 ), BDIAG( 2 ), SUM, 2, BCOEFR, + $ BCOEFI, WORK( 2*N+J ), N, SCALE, TEMP, + $ IINFO ) + IF( SCALE.LT.ONE ) THEN + DO 150 JW = 0, NW - 1 + DO 140 JR = JE, J - 1 + WORK( ( JW+2 )*N+JR ) = SCALE* + $ WORK( ( JW+2 )*N+JR ) + 140 CONTINUE + 150 CONTINUE + XMAX = SCALE*XMAX + END IF + XMAX = MAX( XMAX, TEMP ) + 160 CONTINUE +* +* Copy eigenvector to VL, back transforming if +* HOWMNY='B'. +* + IEIG = IEIG + 1 + IF( ILBACK ) THEN + DO 170 JW = 0, NW - 1 + CALL DGEMV( 'N', N, N+1-JE, ONE, VL( 1, JE ), LDVL, + $ WORK( ( JW+2 )*N+JE ), 1, ZERO, + $ WORK( ( JW+4 )*N+1 ), 1 ) + 170 CONTINUE + CALL DLACPY( ' ', N, NW, WORK( 4*N+1 ), N, VL( 1, JE ), + $ LDVL ) + IBEG = 1 + ELSE + CALL DLACPY( ' ', N, NW, WORK( 2*N+1 ), N, VL( 1, IEIG ), + $ LDVL ) + IBEG = JE + END IF +* +* Scale eigenvector +* + XMAX = ZERO + IF( ILCPLX ) THEN + DO 180 J = IBEG, N + XMAX = MAX( XMAX, ABS( VL( J, IEIG ) )+ + $ ABS( VL( J, IEIG+1 ) ) ) + 180 CONTINUE + ELSE + DO 190 J = IBEG, N + XMAX = MAX( XMAX, ABS( VL( J, IEIG ) ) ) + 190 CONTINUE + END IF +* + IF( XMAX.GT.SAFMIN ) THEN + XSCALE = ONE / XMAX +* + DO 210 JW = 0, NW - 1 + DO 200 JR = IBEG, N + VL( JR, IEIG+JW ) = XSCALE*VL( JR, IEIG+JW ) + 200 CONTINUE + 210 CONTINUE + END IF + IEIG = IEIG + NW - 1 +* + 220 CONTINUE + END IF +* +* Right eigenvectors +* + IF( COMPR ) THEN + IEIG = IM + 1 +* +* Main loop over eigenvalues +* + ILCPLX = .FALSE. + DO 500 JE = N, 1, -1 +* +* Skip this iteration if (a) HOWMNY='S' and SELECT=.FALSE., or +* (b) this would be the second of a complex pair. +* Check for complex eigenvalue, so as to be sure of which +* entry(-ies) of SELECT to look at -- if complex, SELECT(JE) +* or SELECT(JE-1). +* If this is a complex pair, the 2-by-2 diagonal block +* corresponding to the eigenvalue is in rows/columns JE-1:JE +* + IF( ILCPLX ) THEN + ILCPLX = .FALSE. + GO TO 500 + END IF + NW = 1 + IF( JE.GT.1 ) THEN + IF( S( JE, JE-1 ).NE.ZERO ) THEN + ILCPLX = .TRUE. + NW = 2 + END IF + END IF + IF( ILALL ) THEN + ILCOMP = .TRUE. + ELSE IF( ILCPLX ) THEN + ILCOMP = SELECT( JE ) .OR. SELECT( JE-1 ) + ELSE + ILCOMP = SELECT( JE ) + END IF + IF( .NOT.ILCOMP ) + $ GO TO 500 +* +* Decide if (a) singular pencil, (b) real eigenvalue, or +* (c) complex eigenvalue. +* + IF( .NOT.ILCPLX ) THEN + IF( ABS( S( JE, JE ) ).LE.SAFMIN .AND. + $ ABS( P( JE, JE ) ).LE.SAFMIN ) THEN +* +* Singular matrix pencil -- unit eigenvector +* + IEIG = IEIG - 1 + DO 230 JR = 1, N + VR( JR, IEIG ) = ZERO + 230 CONTINUE + VR( IEIG, IEIG ) = ONE + GO TO 500 + END IF + END IF +* +* Clear vector +* + DO 250 JW = 0, NW - 1 + DO 240 JR = 1, N + WORK( ( JW+2 )*N+JR ) = ZERO + 240 CONTINUE + 250 CONTINUE +* +* Compute coefficients in ( a A - b B ) x = 0 +* a is ACOEF +* b is BCOEFR + i*BCOEFI +* + IF( .NOT.ILCPLX ) THEN +* +* Real eigenvalue +* + TEMP = ONE / MAX( ABS( S( JE, JE ) )*ASCALE, + $ ABS( P( JE, JE ) )*BSCALE, SAFMIN ) + SALFAR = ( TEMP*S( JE, JE ) )*ASCALE + SBETA = ( TEMP*P( JE, JE ) )*BSCALE + ACOEF = SBETA*ASCALE + BCOEFR = SALFAR*BSCALE + BCOEFI = ZERO +* +* Scale to avoid underflow +* + SCALE = ONE + LSA = ABS( SBETA ).GE.SAFMIN .AND. ABS( ACOEF ).LT.SMALL + LSB = ABS( SALFAR ).GE.SAFMIN .AND. ABS( BCOEFR ).LT. + $ SMALL + IF( LSA ) + $ SCALE = ( SMALL / ABS( SBETA ) )*MIN( ANORM, BIG ) + IF( LSB ) + $ SCALE = MAX( SCALE, ( SMALL / ABS( SALFAR ) )* + $ MIN( BNORM, BIG ) ) + IF( LSA .OR. LSB ) THEN + SCALE = MIN( SCALE, ONE / + $ ( SAFMIN*MAX( ONE, ABS( ACOEF ), + $ ABS( BCOEFR ) ) ) ) + IF( LSA ) THEN + ACOEF = ASCALE*( SCALE*SBETA ) + ELSE + ACOEF = SCALE*ACOEF + END IF + IF( LSB ) THEN + BCOEFR = BSCALE*( SCALE*SALFAR ) + ELSE + BCOEFR = SCALE*BCOEFR + END IF + END IF + ACOEFA = ABS( ACOEF ) + BCOEFA = ABS( BCOEFR ) +* +* First component is 1 +* + WORK( 2*N+JE ) = ONE + XMAX = ONE +* +* Compute contribution from column JE of A and B to sum +* (See "Further Details", above.) +* + DO 260 JR = 1, JE - 1 + WORK( 2*N+JR ) = BCOEFR*P( JR, JE ) - + $ ACOEF*S( JR, JE ) + 260 CONTINUE + ELSE +* +* Complex eigenvalue +* + CALL DLAG2( S( JE-1, JE-1 ), LDS, P( JE-1, JE-1 ), LDP, + $ SAFMIN*SAFETY, ACOEF, TEMP, BCOEFR, TEMP2, + $ BCOEFI ) + IF( BCOEFI.EQ.ZERO ) THEN + INFO = JE - 1 + RETURN + END IF +* +* Scale to avoid over/underflow +* + ACOEFA = ABS( ACOEF ) + BCOEFA = ABS( BCOEFR ) + ABS( BCOEFI ) + SCALE = ONE + IF( ACOEFA*ULP.LT.SAFMIN .AND. ACOEFA.GE.SAFMIN ) + $ SCALE = ( SAFMIN / ULP ) / ACOEFA + IF( BCOEFA*ULP.LT.SAFMIN .AND. BCOEFA.GE.SAFMIN ) + $ SCALE = MAX( SCALE, ( SAFMIN / ULP ) / BCOEFA ) + IF( SAFMIN*ACOEFA.GT.ASCALE ) + $ SCALE = ASCALE / ( SAFMIN*ACOEFA ) + IF( SAFMIN*BCOEFA.GT.BSCALE ) + $ SCALE = MIN( SCALE, BSCALE / ( SAFMIN*BCOEFA ) ) + IF( SCALE.NE.ONE ) THEN + ACOEF = SCALE*ACOEF + ACOEFA = ABS( ACOEF ) + BCOEFR = SCALE*BCOEFR + BCOEFI = SCALE*BCOEFI + BCOEFA = ABS( BCOEFR ) + ABS( BCOEFI ) + END IF +* +* Compute first two components of eigenvector +* and contribution to sums +* + TEMP = ACOEF*S( JE, JE-1 ) + TEMP2R = ACOEF*S( JE, JE ) - BCOEFR*P( JE, JE ) + TEMP2I = -BCOEFI*P( JE, JE ) + IF( ABS( TEMP ).GE.ABS( TEMP2R )+ABS( TEMP2I ) ) THEN + WORK( 2*N+JE ) = ONE + WORK( 3*N+JE ) = ZERO + WORK( 2*N+JE-1 ) = -TEMP2R / TEMP + WORK( 3*N+JE-1 ) = -TEMP2I / TEMP + ELSE + WORK( 2*N+JE-1 ) = ONE + WORK( 3*N+JE-1 ) = ZERO + TEMP = ACOEF*S( JE-1, JE ) + WORK( 2*N+JE ) = ( BCOEFR*P( JE-1, JE-1 )-ACOEF* + $ S( JE-1, JE-1 ) ) / TEMP + WORK( 3*N+JE ) = BCOEFI*P( JE-1, JE-1 ) / TEMP + END IF +* + XMAX = MAX( ABS( WORK( 2*N+JE ) )+ABS( WORK( 3*N+JE ) ), + $ ABS( WORK( 2*N+JE-1 ) )+ABS( WORK( 3*N+JE-1 ) ) ) +* +* Compute contribution from columns JE and JE-1 +* of A and B to the sums. +* + CREALA = ACOEF*WORK( 2*N+JE-1 ) + CIMAGA = ACOEF*WORK( 3*N+JE-1 ) + CREALB = BCOEFR*WORK( 2*N+JE-1 ) - + $ BCOEFI*WORK( 3*N+JE-1 ) + CIMAGB = BCOEFI*WORK( 2*N+JE-1 ) + + $ BCOEFR*WORK( 3*N+JE-1 ) + CRE2A = ACOEF*WORK( 2*N+JE ) + CIM2A = ACOEF*WORK( 3*N+JE ) + CRE2B = BCOEFR*WORK( 2*N+JE ) - BCOEFI*WORK( 3*N+JE ) + CIM2B = BCOEFI*WORK( 2*N+JE ) + BCOEFR*WORK( 3*N+JE ) + DO 270 JR = 1, JE - 2 + WORK( 2*N+JR ) = -CREALA*S( JR, JE-1 ) + + $ CREALB*P( JR, JE-1 ) - + $ CRE2A*S( JR, JE ) + CRE2B*P( JR, JE ) + WORK( 3*N+JR ) = -CIMAGA*S( JR, JE-1 ) + + $ CIMAGB*P( JR, JE-1 ) - + $ CIM2A*S( JR, JE ) + CIM2B*P( JR, JE ) + 270 CONTINUE + END IF +* + DMIN = MAX( ULP*ACOEFA*ANORM, ULP*BCOEFA*BNORM, SAFMIN ) +* +* Columnwise triangular solve of (a A - b B) x = 0 +* + IL2BY2 = .FALSE. + DO 370 J = JE - NW, 1, -1 +* +* If a 2-by-2 block, is in position j-1:j, wait until +* next iteration to process it (when it will be j:j+1) +* + IF( .NOT.IL2BY2 .AND. J.GT.1 ) THEN + IF( S( J, J-1 ).NE.ZERO ) THEN + IL2BY2 = .TRUE. + GO TO 370 + END IF + END IF + BDIAG( 1 ) = P( J, J ) + IF( IL2BY2 ) THEN + NA = 2 + BDIAG( 2 ) = P( J+1, J+1 ) + ELSE + NA = 1 + END IF +* +* Compute x(j) (and x(j+1), if 2-by-2 block) +* + CALL DLALN2( .FALSE., NA, NW, DMIN, ACOEF, S( J, J ), + $ LDS, BDIAG( 1 ), BDIAG( 2 ), WORK( 2*N+J ), + $ N, BCOEFR, BCOEFI, SUM, 2, SCALE, TEMP, + $ IINFO ) + IF( SCALE.LT.ONE ) THEN +* + DO 290 JW = 0, NW - 1 + DO 280 JR = 1, JE + WORK( ( JW+2 )*N+JR ) = SCALE* + $ WORK( ( JW+2 )*N+JR ) + 280 CONTINUE + 290 CONTINUE + END IF + XMAX = MAX( SCALE*XMAX, TEMP ) +* + DO 310 JW = 1, NW + DO 300 JA = 1, NA + WORK( ( JW+1 )*N+J+JA-1 ) = SUM( JA, JW ) + 300 CONTINUE + 310 CONTINUE +* +* w = w + x(j)*(a S(*,j) - b P(*,j) ) with scaling +* + IF( J.GT.1 ) THEN +* +* Check whether scaling is necessary for sum. +* + XSCALE = ONE / MAX( ONE, XMAX ) + TEMP = ACOEFA*WORK( J ) + BCOEFA*WORK( N+J ) + IF( IL2BY2 ) + $ TEMP = MAX( TEMP, ACOEFA*WORK( J+1 )+BCOEFA* + $ WORK( N+J+1 ) ) + TEMP = MAX( TEMP, ACOEFA, BCOEFA ) + IF( TEMP.GT.BIGNUM*XSCALE ) THEN +* + DO 330 JW = 0, NW - 1 + DO 320 JR = 1, JE + WORK( ( JW+2 )*N+JR ) = XSCALE* + $ WORK( ( JW+2 )*N+JR ) + 320 CONTINUE + 330 CONTINUE + XMAX = XMAX*XSCALE + END IF +* +* Compute the contributions of the off-diagonals of +* column j (and j+1, if 2-by-2 block) of A and B to the +* sums. +* +* + DO 360 JA = 1, NA + IF( ILCPLX ) THEN + CREALA = ACOEF*WORK( 2*N+J+JA-1 ) + CIMAGA = ACOEF*WORK( 3*N+J+JA-1 ) + CREALB = BCOEFR*WORK( 2*N+J+JA-1 ) - + $ BCOEFI*WORK( 3*N+J+JA-1 ) + CIMAGB = BCOEFI*WORK( 2*N+J+JA-1 ) + + $ BCOEFR*WORK( 3*N+J+JA-1 ) + DO 340 JR = 1, J - 1 + WORK( 2*N+JR ) = WORK( 2*N+JR ) - + $ CREALA*S( JR, J+JA-1 ) + + $ CREALB*P( JR, J+JA-1 ) + WORK( 3*N+JR ) = WORK( 3*N+JR ) - + $ CIMAGA*S( JR, J+JA-1 ) + + $ CIMAGB*P( JR, J+JA-1 ) + 340 CONTINUE + ELSE + CREALA = ACOEF*WORK( 2*N+J+JA-1 ) + CREALB = BCOEFR*WORK( 2*N+J+JA-1 ) + DO 350 JR = 1, J - 1 + WORK( 2*N+JR ) = WORK( 2*N+JR ) - + $ CREALA*S( JR, J+JA-1 ) + + $ CREALB*P( JR, J+JA-1 ) + 350 CONTINUE + END IF + 360 CONTINUE + END IF +* + IL2BY2 = .FALSE. + 370 CONTINUE +* +* Copy eigenvector to VR, back transforming if +* HOWMNY='B'. +* + IEIG = IEIG - NW + IF( ILBACK ) THEN +* + DO 410 JW = 0, NW - 1 + DO 380 JR = 1, N + WORK( ( JW+4 )*N+JR ) = WORK( ( JW+2 )*N+1 )* + $ VR( JR, 1 ) + 380 CONTINUE +* +* A series of compiler directives to defeat +* vectorization for the next loop +* +* + DO 400 JC = 2, JE + DO 390 JR = 1, N + WORK( ( JW+4 )*N+JR ) = WORK( ( JW+4 )*N+JR ) + + $ WORK( ( JW+2 )*N+JC )*VR( JR, JC ) + 390 CONTINUE + 400 CONTINUE + 410 CONTINUE +* + DO 430 JW = 0, NW - 1 + DO 420 JR = 1, N + VR( JR, IEIG+JW ) = WORK( ( JW+4 )*N+JR ) + 420 CONTINUE + 430 CONTINUE +* + IEND = N + ELSE + DO 450 JW = 0, NW - 1 + DO 440 JR = 1, N + VR( JR, IEIG+JW ) = WORK( ( JW+2 )*N+JR ) + 440 CONTINUE + 450 CONTINUE +* + IEND = JE + END IF +* +* Scale eigenvector +* + XMAX = ZERO + IF( ILCPLX ) THEN + DO 460 J = 1, IEND + XMAX = MAX( XMAX, ABS( VR( J, IEIG ) )+ + $ ABS( VR( J, IEIG+1 ) ) ) + 460 CONTINUE + ELSE + DO 470 J = 1, IEND + XMAX = MAX( XMAX, ABS( VR( J, IEIG ) ) ) + 470 CONTINUE + END IF +* + IF( XMAX.GT.SAFMIN ) THEN + XSCALE = ONE / XMAX + DO 490 JW = 0, NW - 1 + DO 480 JR = 1, IEND + VR( JR, IEIG+JW ) = XSCALE*VR( JR, IEIG+JW ) + 480 CONTINUE + 490 CONTINUE + END IF + 500 CONTINUE + END IF +* + RETURN +* +* End of DTGEVC +* + END |