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view libcruft/blas/ztrsm.f @ 2329:30c606bec7a8
[project @ 1996-07-19 01:29:05 by jwe]
Initial revision
| author | jwe |
|---|---|
| date | Fri, 19 Jul 1996 01:29:55 +0000 |
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SUBROUTINE ZTRSM ( SIDE, UPLO, TRANSA, DIAG, M, N, ALPHA, A, LDA, $ B, LDB ) * .. Scalar Arguments .. CHARACTER*1 SIDE, UPLO, TRANSA, DIAG INTEGER M, N, LDA, LDB COMPLEX*16 ALPHA * .. Array Arguments .. COMPLEX*16 A( LDA, * ), B( LDB, * ) * .. * * Purpose * ======= * * ZTRSM solves one of the matrix equations * * op( A )*X = alpha*B, or X*op( A ) = alpha*B, * * where alpha is a scalar, X and B are m by n matrices, A is a unit, or * non-unit, upper or lower triangular matrix and op( A ) is one of * * op( A ) = A or op( A ) = A' or op( A ) = conjg( A' ). * * The matrix X is overwritten on B. * * Parameters * ========== * * SIDE - CHARACTER*1. * On entry, SIDE specifies whether op( A ) appears on the left * or right of X as follows: * * SIDE = 'L' or 'l' op( A )*X = alpha*B. * * SIDE = 'R' or 'r' X*op( A ) = alpha*B. * * Unchanged on exit. * * UPLO - CHARACTER*1. * On entry, UPLO specifies whether the matrix A is an upper or * lower triangular matrix as follows: * * UPLO = 'U' or 'u' A is an upper triangular matrix. * * UPLO = 'L' or 'l' A is a lower triangular matrix. * * Unchanged on exit. * * TRANSA - CHARACTER*1. * On entry, TRANSA specifies the form of op( A ) to be used in * the matrix multiplication as follows: * * TRANSA = 'N' or 'n' op( A ) = A. * * TRANSA = 'T' or 't' op( A ) = A'. * * TRANSA = 'C' or 'c' op( A ) = conjg( A' ). * * Unchanged on exit. * * DIAG - CHARACTER*1. * On entry, DIAG specifies whether or not A is unit triangular * as follows: * * DIAG = 'U' or 'u' A is assumed to be unit triangular. * * DIAG = 'N' or 'n' A is not assumed to be unit * triangular. * * Unchanged on exit. * * M - INTEGER. * On entry, M specifies the number of rows of B. M must be at * least zero. * Unchanged on exit. * * N - INTEGER. * On entry, N specifies the number of columns of B. N must be * at least zero. * Unchanged on exit. * * ALPHA - COMPLEX*16 . * On entry, ALPHA specifies the scalar alpha. When alpha is * zero then A is not referenced and B need not be set before * entry. * Unchanged on exit. * * A - COMPLEX*16 array of DIMENSION ( LDA, k ), where k is m * when SIDE = 'L' or 'l' and is n when SIDE = 'R' or 'r'. * Before entry with UPLO = 'U' or 'u', the leading k by k * upper triangular part of the array A must contain the upper * triangular matrix and the strictly lower triangular part of * A is not referenced. * Before entry with UPLO = 'L' or 'l', the leading k by k * lower triangular part of the array A must contain the lower * triangular matrix and the strictly upper triangular part of * A is not referenced. * Note that when DIAG = 'U' or 'u', the diagonal elements of * A are not referenced either, but are assumed to be unity. * Unchanged on exit. * * LDA - INTEGER. * On entry, LDA specifies the first dimension of A as declared * in the calling (sub) program. When SIDE = 'L' or 'l' then * LDA must be at least max( 1, m ), when SIDE = 'R' or 'r' * then LDA must be at least max( 1, n ). * Unchanged on exit. * * B - COMPLEX*16 array of DIMENSION ( LDB, n ). * Before entry, the leading m by n part of the array B must * contain the right-hand side matrix B, and on exit is * overwritten by the solution matrix X. * * LDB - INTEGER. * On entry, LDB specifies the first dimension of B as declared * in the calling (sub) program. LDB must be at least * max( 1, m ). * Unchanged on exit. * * * Level 3 Blas routine. * * -- Written on 8-February-1989. * Jack Dongarra, Argonne National Laboratory. * Iain Duff, AERE Harwell. * Jeremy Du Croz, Numerical Algorithms Group Ltd. * Sven Hammarling, Numerical Algorithms Group Ltd. * * * .. External Functions .. LOGICAL LSAME EXTERNAL LSAME * .. External Subroutines .. EXTERNAL XERBLA * .. Intrinsic Functions .. INTRINSIC DCONJG, MAX * .. Local Scalars .. LOGICAL LSIDE, NOCONJ, NOUNIT, UPPER INTEGER I, INFO, J, K, NROWA COMPLEX*16 TEMP * .. Parameters .. COMPLEX*16 ONE PARAMETER ( ONE = ( 1.0D+0, 0.0D+0 ) ) COMPLEX*16 ZERO PARAMETER ( ZERO = ( 0.0D+0, 0.0D+0 ) ) * .. * .. Executable Statements .. * * Test the input parameters. * LSIDE = LSAME( SIDE , 'L' ) IF( LSIDE )THEN NROWA = M ELSE NROWA = N END IF NOCONJ = LSAME( TRANSA, 'T' ) NOUNIT = LSAME( DIAG , 'N' ) UPPER = LSAME( UPLO , 'U' ) * INFO = 0 IF( ( .NOT.LSIDE ).AND. $ ( .NOT.LSAME( SIDE , 'R' ) ) )THEN INFO = 1 ELSE IF( ( .NOT.UPPER ).AND. $ ( .NOT.LSAME( UPLO , 'L' ) ) )THEN INFO = 2 ELSE IF( ( .NOT.LSAME( TRANSA, 'N' ) ).AND. $ ( .NOT.LSAME( TRANSA, 'T' ) ).AND. $ ( .NOT.LSAME( TRANSA, 'C' ) ) )THEN INFO = 3 ELSE IF( ( .NOT.LSAME( DIAG , 'U' ) ).AND. $ ( .NOT.LSAME( DIAG , 'N' ) ) )THEN INFO = 4 ELSE IF( M .LT.0 )THEN INFO = 5 ELSE IF( N .LT.0 )THEN INFO = 6 ELSE IF( LDA.LT.MAX( 1, NROWA ) )THEN INFO = 9 ELSE IF( LDB.LT.MAX( 1, M ) )THEN INFO = 11 END IF IF( INFO.NE.0 )THEN CALL XERBLA( 'ZTRSM ', INFO ) RETURN END IF * * Quick return if possible. * IF( N.EQ.0 ) $ RETURN * * And when alpha.eq.zero. * IF( ALPHA.EQ.ZERO )THEN DO 20, J = 1, N DO 10, I = 1, M B( I, J ) = ZERO 10 CONTINUE 20 CONTINUE RETURN END IF * * Start the operations. * IF( LSIDE )THEN IF( LSAME( TRANSA, 'N' ) )THEN * * Form B := alpha*inv( A )*B. * IF( UPPER )THEN DO 60, J = 1, N IF( ALPHA.NE.ONE )THEN DO 30, I = 1, M B( I, J ) = ALPHA*B( I, J ) 30 CONTINUE END IF DO 50, K = M, 1, -1 IF( B( K, J ).NE.ZERO )THEN IF( NOUNIT ) $ B( K, J ) = B( K, J )/A( K, K ) DO 40, I = 1, K - 1 B( I, J ) = B( I, J ) - B( K, J )*A( I, K ) 40 CONTINUE END IF 50 CONTINUE 60 CONTINUE ELSE DO 100, J = 1, N IF( ALPHA.NE.ONE )THEN DO 70, I = 1, M B( I, J ) = ALPHA*B( I, J ) 70 CONTINUE END IF DO 90 K = 1, M IF( B( K, J ).NE.ZERO )THEN IF( NOUNIT ) $ B( K, J ) = B( K, J )/A( K, K ) DO 80, I = K + 1, M B( I, J ) = B( I, J ) - B( K, J )*A( I, K ) 80 CONTINUE END IF 90 CONTINUE 100 CONTINUE END IF ELSE * * Form B := alpha*inv( A' )*B * or B := alpha*inv( conjg( A' ) )*B. * IF( UPPER )THEN DO 140, J = 1, N DO 130, I = 1, M TEMP = ALPHA*B( I, J ) IF( NOCONJ )THEN DO 110, K = 1, I - 1 TEMP = TEMP - A( K, I )*B( K, J ) 110 CONTINUE IF( NOUNIT ) $ TEMP = TEMP/A( I, I ) ELSE DO 120, K = 1, I - 1 TEMP = TEMP - DCONJG( A( K, I ) )*B( K, J ) 120 CONTINUE IF( NOUNIT ) $ TEMP = TEMP/DCONJG( A( I, I ) ) END IF B( I, J ) = TEMP 130 CONTINUE 140 CONTINUE ELSE DO 180, J = 1, N DO 170, I = M, 1, -1 TEMP = ALPHA*B( I, J ) IF( NOCONJ )THEN DO 150, K = I + 1, M TEMP = TEMP - A( K, I )*B( K, J ) 150 CONTINUE IF( NOUNIT ) $ TEMP = TEMP/A( I, I ) ELSE DO 160, K = I + 1, M TEMP = TEMP - DCONJG( A( K, I ) )*B( K, J ) 160 CONTINUE IF( NOUNIT ) $ TEMP = TEMP/DCONJG( A( I, I ) ) END IF B( I, J ) = TEMP 170 CONTINUE 180 CONTINUE END IF END IF ELSE IF( LSAME( TRANSA, 'N' ) )THEN * * Form B := alpha*B*inv( A ). * IF( UPPER )THEN DO 230, J = 1, N IF( ALPHA.NE.ONE )THEN DO 190, I = 1, M B( I, J ) = ALPHA*B( I, J ) 190 CONTINUE END IF DO 210, K = 1, J - 1 IF( A( K, J ).NE.ZERO )THEN DO 200, I = 1, M B( I, J ) = B( I, J ) - A( K, J )*B( I, K ) 200 CONTINUE END IF 210 CONTINUE IF( NOUNIT )THEN TEMP = ONE/A( J, J ) DO 220, I = 1, M B( I, J ) = TEMP*B( I, J ) 220 CONTINUE END IF 230 CONTINUE ELSE DO 280, J = N, 1, -1 IF( ALPHA.NE.ONE )THEN DO 240, I = 1, M B( I, J ) = ALPHA*B( I, J ) 240 CONTINUE END IF DO 260, K = J + 1, N IF( A( K, J ).NE.ZERO )THEN DO 250, I = 1, M B( I, J ) = B( I, J ) - A( K, J )*B( I, K ) 250 CONTINUE END IF 260 CONTINUE IF( NOUNIT )THEN TEMP = ONE/A( J, J ) DO 270, I = 1, M B( I, J ) = TEMP*B( I, J ) 270 CONTINUE END IF 280 CONTINUE END IF ELSE * * Form B := alpha*B*inv( A' ) * or B := alpha*B*inv( conjg( A' ) ). * IF( UPPER )THEN DO 330, K = N, 1, -1 IF( NOUNIT )THEN IF( NOCONJ )THEN TEMP = ONE/A( K, K ) ELSE TEMP = ONE/DCONJG( A( K, K ) ) END IF DO 290, I = 1, M B( I, K ) = TEMP*B( I, K ) 290 CONTINUE END IF DO 310, J = 1, K - 1 IF( A( J, K ).NE.ZERO )THEN IF( NOCONJ )THEN TEMP = A( J, K ) ELSE TEMP = DCONJG( A( J, K ) ) END IF DO 300, I = 1, M B( I, J ) = B( I, J ) - TEMP*B( I, K ) 300 CONTINUE END IF 310 CONTINUE IF( ALPHA.NE.ONE )THEN DO 320, I = 1, M B( I, K ) = ALPHA*B( I, K ) 320 CONTINUE END IF 330 CONTINUE ELSE DO 380, K = 1, N IF( NOUNIT )THEN IF( NOCONJ )THEN TEMP = ONE/A( K, K ) ELSE TEMP = ONE/DCONJG( A( K, K ) ) END IF DO 340, I = 1, M B( I, K ) = TEMP*B( I, K ) 340 CONTINUE END IF DO 360, J = K + 1, N IF( A( J, K ).NE.ZERO )THEN IF( NOCONJ )THEN TEMP = A( J, K ) ELSE TEMP = DCONJG( A( J, K ) ) END IF DO 350, I = 1, M B( I, J ) = B( I, J ) - TEMP*B( I, K ) 350 CONTINUE END IF 360 CONTINUE IF( ALPHA.NE.ONE )THEN DO 370, I = 1, M B( I, K ) = ALPHA*B( I, K ) 370 CONTINUE END IF 380 CONTINUE END IF END IF END IF * RETURN * * End of ZTRSM . * END