1CHEMM(1) BLAS routine CHEMM(1)
2
6 CHEMM - performs one of the matrix-matrix operations C := alpha*A*B +
7 beta*C,
8
10 SUBROUTINE CHEMM(SIDE,UPLO,M,N,ALPHA,A,LDA,B,LDB,BETA,C,LDC)
11 COMPLEX ALPHA,BETA
13 INTEGER LDA,LDB,LDC,M,N
15 CHARACTER SIDE,UPLO
17 COMPLEX A(LDA,*),B(LDB,*),C(LDC,*)
19
21 CHEMM performs one of the matrix-matrix operations
22 or
24 C := alpha*B*A + beta*C,
26 where alpha and beta are scalars, A is an hermitian matrix and B and C
28 are m by n matrices.
29
32 SIDE - CHARACTER*1.
33 On entry, SIDE specifies whether the hermitian matrix A
34 appears on the left or right in the operation as follows:
35 SIDE = 'L' or 'l' C := alpha*A*B + beta*C,
37 SIDE = 'R' or 'r' C := alpha*B*A + beta*C,
39 Unchanged on exit.
41 UPLO - CHARACTER*1.
43 On entry, UPLO specifies whether the upper or lower
44 triangular part of the hermitian matrix A is to be
45 referenced as follows:
46 UPLO = 'U' or 'u' Only the upper triangular part of the her‐
48 mitian matrix is to be referenced.
49 UPLO = 'L' or 'l' Only the lower triangular part of the her‐
51 mitian matrix is to be referenced.
52 Unchanged on exit.
54 M - INTEGER.
56 On entry, M specifies the number of rows of the matrix C. M
57 must be at least zero. Unchanged on exit.
58 N - INTEGER.
60 On entry, N specifies the number of columns of the matrix C. N
61 must be at least zero. Unchanged on exit.
62 ALPHA - COMPLEX .
64 On entry, ALPHA specifies the scalar alpha. Unchanged on exit.
65 A - COMPLEX array of DIMENSION ( LDA, ka ), where ka is
67 m when SIDE = 'L' or 'l' and is n otherwise. Before entry
68 with SIDE = 'L' or 'l', the m by m part of the array A
69 must contain the hermitian matrix, such that when UPLO = 'U'
70 or 'u', the leading m by m upper triangular part of the array A
71 must contain the upper triangular part of the hermitian matrix
72 and the strictly lower triangular part of A is not refer‐
73 enced, and when UPLO = 'L' or 'l', the leading m by m lower
74 triangular part of the array A must contain the lower tri‐
75 angular part of the hermitian matrix and the strictly upper
76 triangular part of A is not referenced. Before entry with
77 SIDE = 'R' or 'r', the n by n part of the array A must con‐
78 tain the hermitian matrix, such that when UPLO = 'U' or 'u',
79 the leading n by n upper triangular part of the array A must
80 contain the upper triangular part of the hermitian matrix and
81 the strictly lower triangular part of A is not referenced,
82 and when UPLO = 'L' or 'l', the leading n by n lower triangu‐
83 lar part of the array A must contain the lower triangular
84 part of the hermitian matrix and the strictly upper triangu‐
85 lar part of A is not referenced. Note that the imaginary
86 parts of the diagonal elements need not be set, they are
87 assumed to be zero. Unchanged on exit.
88 LDA - INTEGER.
90 On entry, LDA specifies the first dimension of A as declared in
91 the calling (sub) program. When SIDE = 'L' or 'l' then LDA
92 must be at least max( 1, m ), otherwise LDA must be at least
93 max( 1, n ). Unchanged on exit.
94 B - COMPLEX array of DIMENSION ( LDB, n ).
96 Before entry, the leading m by n part of the array B must
97 contain the matrix B. Unchanged on exit.
98 LDB - INTEGER.
100 On entry, LDB specifies the first dimension of B as declared in
101 the calling (sub) program. LDB must be at least max( 1,
102 m ). Unchanged on exit.
103 BETA - COMPLEX .
105 On entry, BETA specifies the scalar beta. When BETA is
106 supplied as zero then C need not be set on input. Unchanged on
107 exit.
108 C - COMPLEX array of DIMENSION ( LDC, n ).
110 Before entry, the leading m by n part of the array C must
111 contain the matrix C, except when beta is zero, in which
112 case C need not be set on entry. On exit, the array C is
113 overwritten by the m by n updated matrix.
114 LDC - INTEGER.
116 On entry, LDC specifies the first dimension of C as declared in
117 the calling (sub) program. LDC must be at least max( 1,
118 m ). Unchanged on exit.
119
121 Level 3 Blas routine.
122 -- Written on 8-February-1989.
124 Jack Dongarra, Argonne National Laboratory.
125 Iain Duff, AERE Harwell.
126 Jeremy Du Croz, Numerical Algorithms Group Ltd.
127 Sven Hammarling, Numerical Algorithms Group Ltd.
128BLAS routine November 2008 CHEMM(1)