diff options
Diffstat (limited to 'src/fortran/blas/dsyr2k.f')
| -rw-r--r-- | src/fortran/blas/dsyr2k.f | 327 |
1 files changed, 327 insertions, 0 deletions
diff --git a/src/fortran/blas/dsyr2k.f b/src/fortran/blas/dsyr2k.f new file mode 100644 index 0000000..ac7d97d --- /dev/null +++ b/src/fortran/blas/dsyr2k.f @@ -0,0 +1,327 @@ + SUBROUTINE DSYR2K( UPLO, TRANS, N, K, ALPHA, A, LDA, B, LDB, + $ BETA, C, LDC ) +* .. Scalar Arguments .. + CHARACTER*1 UPLO, TRANS + INTEGER N, K, LDA, LDB, LDC + DOUBLE PRECISION ALPHA, BETA +* .. Array Arguments .. + DOUBLE PRECISION A( LDA, * ), B( LDB, * ), C( LDC, * ) +* .. +* +* Purpose +* ======= +* +* DSYR2K performs one of the symmetric rank 2k operations +* +* C := alpha*A*B' + alpha*B*A' + beta*C, +* +* or +* +* C := alpha*A'*B + alpha*B'*A + beta*C, +* +* where alpha and beta are scalars, C is an n by n symmetric matrix +* and A and B are n by k matrices in the first case and k by n +* matrices in the second case. +* +* Parameters +* ========== +* +* UPLO - CHARACTER*1. +* On entry, UPLO specifies whether the upper or lower +* triangular part of the array C is to be referenced as +* follows: +* +* UPLO = 'U' or 'u' Only the upper triangular part of C +* is to be referenced. +* +* UPLO = 'L' or 'l' Only the lower triangular part of C +* is to be referenced. +* +* Unchanged on exit. +* +* TRANS - CHARACTER*1. +* On entry, TRANS specifies the operation to be performed as +* follows: +* +* TRANS = 'N' or 'n' C := alpha*A*B' + alpha*B*A' + +* beta*C. +* +* TRANS = 'T' or 't' C := alpha*A'*B + alpha*B'*A + +* beta*C. +* +* TRANS = 'C' or 'c' C := alpha*A'*B + alpha*B'*A + +* beta*C. +* +* Unchanged on exit. +* +* N - INTEGER. +* On entry, N specifies the order of the matrix C. N must be +* at least zero. +* Unchanged on exit. +* +* K - INTEGER. +* On entry with TRANS = 'N' or 'n', K specifies the number +* of columns of the matrices A and B, and on entry with +* TRANS = 'T' or 't' or 'C' or 'c', K specifies the number +* of rows of the matrices A and B. K must be at least zero. +* Unchanged on exit. +* +* ALPHA - DOUBLE PRECISION. +* On entry, ALPHA specifies the scalar alpha. +* Unchanged on exit. +* +* A - DOUBLE PRECISION array of DIMENSION ( LDA, ka ), where ka is +* k when TRANS = 'N' or 'n', and is n otherwise. +* Before entry with TRANS = 'N' or 'n', the leading n by k +* part of the array A must contain the matrix A, otherwise +* the leading k by n part of the array A must contain the +* matrix A. +* Unchanged on exit. +* +* LDA - INTEGER. +* On entry, LDA specifies the first dimension of A as declared +* in the calling (sub) program. When TRANS = 'N' or 'n' +* then LDA must be at least max( 1, n ), otherwise LDA must +* be at least max( 1, k ). +* Unchanged on exit. +* +* B - DOUBLE PRECISION array of DIMENSION ( LDB, kb ), where kb is +* k when TRANS = 'N' or 'n', and is n otherwise. +* Before entry with TRANS = 'N' or 'n', the leading n by k +* part of the array B must contain the matrix B, otherwise +* the leading k by n part of the array B must contain the +* matrix B. +* Unchanged on exit. +* +* LDB - INTEGER. +* On entry, LDB specifies the first dimension of B as declared +* in the calling (sub) program. When TRANS = 'N' or 'n' +* then LDB must be at least max( 1, n ), otherwise LDB must +* be at least max( 1, k ). +* Unchanged on exit. +* +* BETA - DOUBLE PRECISION. +* On entry, BETA specifies the scalar beta. +* Unchanged on exit. +* +* C - DOUBLE PRECISION array of DIMENSION ( LDC, n ). +* Before entry with UPLO = 'U' or 'u', the leading n by n +* upper triangular part of the array C must contain the upper +* triangular part of the symmetric matrix and the strictly +* lower triangular part of C is not referenced. On exit, the +* upper triangular part of the array C is overwritten by the +* upper triangular part of the updated matrix. +* Before entry with UPLO = 'L' or 'l', the leading n by n +* lower triangular part of the array C must contain the lower +* triangular part of the symmetric matrix and the strictly +* upper triangular part of C is not referenced. On exit, the +* lower triangular part of the array C is overwritten by the +* lower triangular part of the updated matrix. +* +* LDC - INTEGER. +* On entry, LDC specifies the first dimension of C as declared +* in the calling (sub) program. LDC must be at least +* max( 1, n ). +* 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 MAX +* .. Local Scalars .. + LOGICAL UPPER + INTEGER I, INFO, J, L, NROWA + DOUBLE PRECISION TEMP1, TEMP2 +* .. Parameters .. + DOUBLE PRECISION ONE , ZERO + PARAMETER ( ONE = 1.0D+0, ZERO = 0.0D+0 ) +* .. +* .. Executable Statements .. +* +* Test the input parameters. +* + IF( LSAME( TRANS, 'N' ) )THEN + NROWA = N + ELSE + NROWA = K + END IF + UPPER = LSAME( UPLO, 'U' ) +* + INFO = 0 + IF( ( .NOT.UPPER ).AND. + $ ( .NOT.LSAME( UPLO , 'L' ) ) )THEN + INFO = 1 + ELSE IF( ( .NOT.LSAME( TRANS, 'N' ) ).AND. + $ ( .NOT.LSAME( TRANS, 'T' ) ).AND. + $ ( .NOT.LSAME( TRANS, 'C' ) ) )THEN + INFO = 2 + ELSE IF( N .LT.0 )THEN + INFO = 3 + ELSE IF( K .LT.0 )THEN + INFO = 4 + ELSE IF( LDA.LT.MAX( 1, NROWA ) )THEN + INFO = 7 + ELSE IF( LDB.LT.MAX( 1, NROWA ) )THEN + INFO = 9 + ELSE IF( LDC.LT.MAX( 1, N ) )THEN + INFO = 12 + END IF + IF( INFO.NE.0 )THEN + CALL XERBLA( 'DSYR2K', INFO ) + RETURN + END IF +* +* Quick return if possible. +* + IF( ( N.EQ.0 ).OR. + $ ( ( ( ALPHA.EQ.ZERO ).OR.( K.EQ.0 ) ).AND.( BETA.EQ.ONE ) ) ) + $ RETURN +* +* And when alpha.eq.zero. +* + IF( ALPHA.EQ.ZERO )THEN + IF( UPPER )THEN + IF( BETA.EQ.ZERO )THEN + DO 20, J = 1, N + DO 10, I = 1, J + C( I, J ) = ZERO + 10 CONTINUE + 20 CONTINUE + ELSE + DO 40, J = 1, N + DO 30, I = 1, J + C( I, J ) = BETA*C( I, J ) + 30 CONTINUE + 40 CONTINUE + END IF + ELSE + IF( BETA.EQ.ZERO )THEN + DO 60, J = 1, N + DO 50, I = J, N + C( I, J ) = ZERO + 50 CONTINUE + 60 CONTINUE + ELSE + DO 80, J = 1, N + DO 70, I = J, N + C( I, J ) = BETA*C( I, J ) + 70 CONTINUE + 80 CONTINUE + END IF + END IF + RETURN + END IF +* +* Start the operations. +* + IF( LSAME( TRANS, 'N' ) )THEN +* +* Form C := alpha*A*B' + alpha*B*A' + C. +* + IF( UPPER )THEN + DO 130, J = 1, N + IF( BETA.EQ.ZERO )THEN + DO 90, I = 1, J + C( I, J ) = ZERO + 90 CONTINUE + ELSE IF( BETA.NE.ONE )THEN + DO 100, I = 1, J + C( I, J ) = BETA*C( I, J ) + 100 CONTINUE + END IF + DO 120, L = 1, K + IF( ( A( J, L ).NE.ZERO ).OR. + $ ( B( J, L ).NE.ZERO ) )THEN + TEMP1 = ALPHA*B( J, L ) + TEMP2 = ALPHA*A( J, L ) + DO 110, I = 1, J + C( I, J ) = C( I, J ) + + $ A( I, L )*TEMP1 + B( I, L )*TEMP2 + 110 CONTINUE + END IF + 120 CONTINUE + 130 CONTINUE + ELSE + DO 180, J = 1, N + IF( BETA.EQ.ZERO )THEN + DO 140, I = J, N + C( I, J ) = ZERO + 140 CONTINUE + ELSE IF( BETA.NE.ONE )THEN + DO 150, I = J, N + C( I, J ) = BETA*C( I, J ) + 150 CONTINUE + END IF + DO 170, L = 1, K + IF( ( A( J, L ).NE.ZERO ).OR. + $ ( B( J, L ).NE.ZERO ) )THEN + TEMP1 = ALPHA*B( J, L ) + TEMP2 = ALPHA*A( J, L ) + DO 160, I = J, N + C( I, J ) = C( I, J ) + + $ A( I, L )*TEMP1 + B( I, L )*TEMP2 + 160 CONTINUE + END IF + 170 CONTINUE + 180 CONTINUE + END IF + ELSE +* +* Form C := alpha*A'*B + alpha*B'*A + C. +* + IF( UPPER )THEN + DO 210, J = 1, N + DO 200, I = 1, J + TEMP1 = ZERO + TEMP2 = ZERO + DO 190, L = 1, K + TEMP1 = TEMP1 + A( L, I )*B( L, J ) + TEMP2 = TEMP2 + B( L, I )*A( L, J ) + 190 CONTINUE + IF( BETA.EQ.ZERO )THEN + C( I, J ) = ALPHA*TEMP1 + ALPHA*TEMP2 + ELSE + C( I, J ) = BETA *C( I, J ) + + $ ALPHA*TEMP1 + ALPHA*TEMP2 + END IF + 200 CONTINUE + 210 CONTINUE + ELSE + DO 240, J = 1, N + DO 230, I = J, N + TEMP1 = ZERO + TEMP2 = ZERO + DO 220, L = 1, K + TEMP1 = TEMP1 + A( L, I )*B( L, J ) + TEMP2 = TEMP2 + B( L, I )*A( L, J ) + 220 CONTINUE + IF( BETA.EQ.ZERO )THEN + C( I, J ) = ALPHA*TEMP1 + ALPHA*TEMP2 + ELSE + C( I, J ) = BETA *C( I, J ) + + $ ALPHA*TEMP1 + ALPHA*TEMP2 + END IF + 230 CONTINUE + 240 CONTINUE + END IF + END IF +* + RETURN +* +* End of DSYR2K. +* + END |