Product of a Symmetric Matrix and a General Matrix

Operation	SIDE	Matrix A	Matrix B
	'L' or 'l'	m x m	m x n
	'R' or 'r'	n x n	m x n

Calling Sequence

CALL DSYMM	(SIDE, UPLO, M, N, DALPHA, DA, LDA, DB, LDB, DBETA, DC, LDC)
CALL SSYMM	(SIDE, UPLO, M, N, SALPHA, SA, LDA, SB, LDB, SBETA, SC, LDC)
CALL ZSYMM	(SIDE, UPLO, M, N, ZALPHA, ZA, LDA, ZB, LDB, ZBETA, ZC, LDC)
CALL CSYMM	(SIDE, UPLO, M, N, CALPHA, CA, LDA, CB, LDB, CBETA, CC, LDC)
void dsymm	(char side, char uplo, int m, int n, double dalpha, double *da, int lda, double *db, int ldb, double dbeta, double *dc, int ldc)
void ssymm	(char side, char uplo, int m, int n, float salpha, float *sa, int lda, float *sb, int ldb, float sbeta, float *sc, int ldc)
void zsymm	(char side, char uplo, int m, int n, doublecomplex *zalpha, doublecomplex *za, int lda, doublecomplex * b, int ldb, doublecomplex *zbeta, doublecomplex *zc, int ldc)
void csymm	(char side, char uplo, int m, int n, complex *calpha, complex *ca, int lda, complex *cb, int ldb, complex *cbeta, complex *cc, int ldc)

Arguments

SIDE	Indicates whether the product involving matrices A and B should be formed as AB or BA. The legal values for SIDE are listed below. Any value not listed below is illegal.
	'L' or 'l'	Compute AB.
	'R' or 'r'	Compute BA.
UPLO	Indicates whether the values in a matrix reside in the upper or lower triangle of the array in which it is stored. The legal values for UPLO are listed below. Any value not listed below is illegal.
	'L' or 'l'	Only lower triangle of array will be referenced.
	'U' or 'u'	Only upper triangle of array will be referenced.
M, N	Indicate the size of the matrices as shown in the table above.
xALPHA	Scalar that scales the input value of the matrix stored in A.
xA	Two-dimensional array in which one of the input matrices is stored.
LDA	Leading dimension of the array A as specified in the dimension or type statement. LDA max (1,N).
	If SIDE = 'L' or 'l', LDA max (1,M).
xB	Two-dimensional array in which one of the input matrices is stored.
LDB	Leading dimension of the array B as specified in the dimension or type statement. LDB max (1,M).
xBETA	Scalar that scales the input value of the matrix stored in C.
xC	Two-dimensional array.
	On entry, an input matrix.
	On exit, the result matrix.
LDC	Leading dimension of the array C as specified in the dimension or type statement. LDC max (1,M).

Sample Program

PROGRAM TEST

IMPLICIT NONE

C

INTEGER LDA, LDB, LDC, M, N

PARAMETER (M = 3)

PARAMETER (N = 2)

PARAMETER (LDA = M)

PARAMETER (LDB = M)

PARAMETER (LDC = M)

C

DOUBLE PRECISION A(LDA,M), ALPHA, B(LDB,N), BETA, C(LDC,N)

INTEGER I, J

C

EXTERNAL DSYMM

C

C Initialize the array A to store in symmetric form the

C symmetric matrix A shown below. Initialize the arrays

C B and C to store the matrices B and C shown below.

C

C 1 2 3 0 1 100 100

C A = 2 4 5 B = 1 0 C = 100 100

C 3 5 6 2 2 100 100

C

DATA A / 1.0D0, 2.0D0, 3.0D0, 8D8, 4.0D0, 5.0D0, 8D8, 8D8,

$ 6.0D0 /

DATA B / 0.0D0, 1.0D0, 2.0D0, 1.0D0, 0.0D0, 2.0D0 /

DATA C / 6*1.0D2 /

C

ALPHA = 1.0D0

BETA = 1.0D0

PRINT 1000

DO 100, I = 1, M

PRINT 1010, (A(I,J), J = 1, I), (A(J,I), J = I + 1, M)

100 CONTINUE

PRINT 1020

PRINT 1010, ((A(I,J), J = 1, M), I = 1, M)

PRINT 1030

PRINT 1040, ((B(I,J), J = 1, N), I = 1, M)

PRINT 1050

PRINT 1040, ((C(I,J), J = 1, N), I = 1, M)

CALL DSYMM ('LEFT SIDE A', 'LOWER TRIANGULAR A', M, N,

$ ALPHA, A, LDA, B, LDB, BETA, C, LDC)

PRINT 1060

PRINT 1040, ((C(I,J), J = 1, N), I = 1, M)

C

1000 FORMAT (1X, 'A in full form:')

1010 FORMAT (3(3X, F5.1))

1020 FORMAT (/1X, 'A in symmetric form: (* in unused elements)')

1030 FORMAT (/1X, 'B:')

1040 FORMAT (2(3X, F5.1))

1050 FORMAT (/1X, 'C:')

1060 FORMAT (/1X, 'AB + C:')

C

END

Sample Output

A in full form:
1.0 2.0 3.0
2.0 4.0 5.0
3.0 5.0 6.0
A in symmetric form: (* in unused elements)
1.0 ***** *****
2.0 4.0 *****
3.0 5.0 6.0
B:
0.0 1.0
1.0 0.0
2.0 2.0
C:
100.0 100.0
100.0 100.0
100.0 100.0
AB + C:
108.0 107.0
114.0 112.0
117.0 115.0