Mercurial > octave-nkf
view libcruft/blas/zherk.f @ 4720:e759d01692db ss-2-1-53
[project @ 2004-01-23 04:13:37 by jwe]
| author | jwe |
|---|---|
| date | Fri, 23 Jan 2004 04:13:37 +0000 |
| parents | bac14003d9bb |
| children |
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SUBROUTINE ZHERK( UPLO, TRANS, N, K, ALPHA, A, LDA, BETA, C, LDC ) * .. Scalar Arguments .. CHARACTER TRANS, UPLO INTEGER K, LDA, LDC, N DOUBLE PRECISION ALPHA, BETA * .. * .. Array Arguments .. COMPLEX*16 A( LDA, * ), C( LDC, * ) * .. * * Purpose * ======= * * ZHERK performs one of the hermitian rank k operations * * C := alpha*A*conjg( A' ) + beta*C, * * or * * C := alpha*conjg( A' )*A + beta*C, * * where alpha and beta are real scalars, C is an n by n hermitian * matrix and A is an n by k matrix in the first case and a k by n * matrix 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*conjg( A' ) + beta*C. * * TRANS = 'C' or 'c' C := alpha*conjg( A' )*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 matrix A, and on entry with * TRANS = 'C' or 'c', K specifies the number of rows of the * matrix A. K must be at least zero. * Unchanged on exit. * * ALPHA - DOUBLE PRECISION . * On entry, ALPHA specifies the scalar alpha. * Unchanged on exit. * * A - COMPLEX*16 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. * * BETA - DOUBLE PRECISION. * On entry, BETA specifies the scalar beta. * Unchanged on exit. * * C - COMPLEX*16 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 hermitian 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 hermitian 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. * Note that the imaginary parts of the diagonal elements need * not be set, they are assumed to be zero, and on exit they * are set to zero. * * 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. * * -- Modified 8-Nov-93 to set C(J,J) to DBLE( C(J,J) ) when BETA = 1. * Ed Anderson, Cray Research Inc. * * * .. External Functions .. LOGICAL LSAME EXTERNAL LSAME * .. * .. External Subroutines .. EXTERNAL XERBLA * .. * .. Intrinsic Functions .. INTRINSIC DBLE, DCMPLX, DCONJG, MAX * .. * .. Local Scalars .. LOGICAL UPPER INTEGER I, INFO, J, L, NROWA DOUBLE PRECISION RTEMP COMPLEX*16 TEMP * .. * .. 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, '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( LDC.LT.MAX( 1, N ) ) THEN INFO = 10 END IF IF( INFO.NE.0 ) THEN CALL XERBLA( 'ZHERK ', 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 - 1 C( I, J ) = BETA*C( I, J ) 30 CONTINUE C( J, J ) = BETA*DBLE( C( J, J ) ) 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 C( J, J ) = BETA*DBLE( C( J, J ) ) DO 70 I = J + 1, 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*conjg( A' ) + beta*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 - 1 C( I, J ) = BETA*C( I, J ) 100 CONTINUE C( J, J ) = BETA*DBLE( C( J, J ) ) ELSE C( J, J ) = DBLE( C( J, J ) ) END IF DO 120 L = 1, K IF( A( J, L ).NE.DCMPLX( ZERO ) ) THEN TEMP = ALPHA*DCONJG( A( J, L ) ) DO 110 I = 1, J - 1 C( I, J ) = C( I, J ) + TEMP*A( I, L ) 110 CONTINUE C( J, J ) = DBLE( C( J, J ) ) + $ DBLE( TEMP*A( I, L ) ) 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 C( J, J ) = BETA*DBLE( C( J, J ) ) DO 150 I = J + 1, N C( I, J ) = BETA*C( I, J ) 150 CONTINUE ELSE C( J, J ) = DBLE( C( J, J ) ) END IF DO 170 L = 1, K IF( A( J, L ).NE.DCMPLX( ZERO ) ) THEN TEMP = ALPHA*DCONJG( A( J, L ) ) C( J, J ) = DBLE( C( J, J ) ) + $ DBLE( TEMP*A( J, L ) ) DO 160 I = J + 1, N C( I, J ) = C( I, J ) + TEMP*A( I, L ) 160 CONTINUE END IF 170 CONTINUE 180 CONTINUE END IF ELSE * * Form C := alpha*conjg( A' )*A + beta*C. * IF( UPPER ) THEN DO 220 J = 1, N DO 200 I = 1, J - 1 TEMP = ZERO DO 190 L = 1, K TEMP = TEMP + DCONJG( A( L, I ) )*A( L, J ) 190 CONTINUE IF( BETA.EQ.ZERO ) THEN C( I, J ) = ALPHA*TEMP ELSE C( I, J ) = ALPHA*TEMP + BETA*C( I, J ) END IF 200 CONTINUE RTEMP = ZERO DO 210 L = 1, K RTEMP = RTEMP + DCONJG( A( L, J ) )*A( L, J ) 210 CONTINUE IF( BETA.EQ.ZERO ) THEN C( J, J ) = ALPHA*RTEMP ELSE C( J, J ) = ALPHA*RTEMP + BETA*DBLE( C( J, J ) ) END IF 220 CONTINUE ELSE DO 260 J = 1, N RTEMP = ZERO DO 230 L = 1, K RTEMP = RTEMP + DCONJG( A( L, J ) )*A( L, J ) 230 CONTINUE IF( BETA.EQ.ZERO ) THEN C( J, J ) = ALPHA*RTEMP ELSE C( J, J ) = ALPHA*RTEMP + BETA*DBLE( C( J, J ) ) END IF DO 250 I = J + 1, N TEMP = ZERO DO 240 L = 1, K TEMP = TEMP + DCONJG( A( L, I ) )*A( L, J ) 240 CONTINUE IF( BETA.EQ.ZERO ) THEN C( I, J ) = ALPHA*TEMP ELSE C( I, J ) = ALPHA*TEMP + BETA*C( I, J ) END IF 250 CONTINUE 260 CONTINUE END IF END IF * RETURN * * End of ZHERK . * END