1STRSM(1) BLAS routine STRSM(1)
2
6 STRSM - one of the matrix equations op( A )*X = alpha*B, or X*op( A )
7 = alpha*B,
8
10 SUBROUTINE STRSM(SIDE,UPLO,TRANSA,DIAG,M,N,ALPHA,A,LDA,B,LDB)
11 REAL ALPHA
13 INTEGER LDA,LDB,M,N
15 CHARACTER DIAG,SIDE,TRANSA,UPLO
17 REAL A(LDA,*),B(LDB,*)
19
21 STRSM solves one of the matrix equations
22 where alpha is a scalar, X and B are m by n matrices, A is a unit, or
24 non-unit, upper or lower triangular matrix and op( A ) is one of
25 op( A ) = A or op( A ) = A'.
27 The matrix X is overwritten on B.
29
32 SIDE - CHARACTER*1.
33 On entry, SIDE specifies whether op( A ) appears on the left or
34 right of X as follows:
35 SIDE = 'L' or 'l' op( A )*X = alpha*B.
37 SIDE = 'R' or 'r' X*op( A ) = alpha*B.
39 Unchanged on exit.
41 UPLO - CHARACTER*1.
43 On entry, UPLO specifies whether the matrix A is an upper or
44 lower triangular matrix as follows:
45 UPLO = 'U' or 'u' A is an upper triangular matrix.
47 UPLO = 'L' or 'l' A is a lower triangular matrix.
49 Unchanged on exit.
51 TRANSA - CHARACTER*1. On entry, TRANSA specifies the form of
53 op( A ) to be used in the matrix multiplication as follows:
54 TRANSA = 'N' or 'n' op( A ) = A.
56 TRANSA = 'T' or 't' op( A ) = A'.
58 TRANSA = 'C' or 'c' op( A ) = A'.
60 Unchanged on exit.
62 DIAG - CHARACTER*1.
64 On entry, DIAG specifies whether or not A is unit triangular as
65 follows:
66 DIAG = 'U' or 'u' A is assumed to be unit triangular.
68 DIAG = 'N' or 'n' A is not assumed to be unit triangular.
70 Unchanged on exit.
72 M - INTEGER.
74 On entry, M specifies the number of rows of B. M must be at
75 least zero. Unchanged on exit.
76 N - INTEGER.
78 On entry, N specifies the number of columns of B. N must be at
79 least zero. Unchanged on exit.
80 ALPHA - REAL .
82 On entry, ALPHA specifies the scalar alpha. When alpha is
83 zero then A is not referenced and B need not be set before
84 entry. Unchanged on exit.
85 A - REAL array of DIMENSION ( LDA, k ), where k is m
87 when SIDE = 'L' or 'l' and is n when SIDE = 'R' or 'r'.
88 Before entry with UPLO = 'U' or 'u', the leading k by k
89 upper triangular part of the array A must contain the upper
90 triangular matrix and the strictly lower triangular part of A
91 is not referenced. Before entry with UPLO = 'L' or 'l', the
92 leading k by k lower triangular part of the array A must con‐
93 tain the lower triangular matrix and the strictly upper trian‐
94 gular part of A is not referenced. Note that when DIAG = 'U'
95 or 'u', the diagonal elements of A are not referenced either,
96 but are assumed to be unity. Unchanged on exit.
97 LDA - INTEGER.
99 On entry, LDA specifies the first dimension of A as declared in
100 the calling (sub) program. When SIDE = 'L' or 'l' then LDA
101 must be at least max( 1, m ), when SIDE = 'R' or 'r' then LDA
102 must be at least max( 1, n ). Unchanged on exit.
103 B - REAL array of DIMENSION ( LDB, n ).
105 Before entry, the leading m by n part of the array B must
106 contain the right-hand side matrix B, and on exit is
107 overwritten by the solution matrix X.
108 LDB - INTEGER.
110 On entry, LDB specifies the first dimension of B as declared in
111 the calling (sub) program. LDB must be at least max( 1,
112 m ). Unchanged on exit.
113 Level 3 Blas routine.
115 -- Written on 8-February-1989. Jack Dongarra, Argonne National
117 Laboratory. Iain Duff, AERE Harwell. Jeremy Du Croz, Numerical
118 Algorithms Group Ltd. Sven Hammarling, Numerical Algorithms
119 Group Ltd.
120BLAS routine November 2006 STRSM(1)