1SGEMV(1)                         BLAS routine                         SGEMV(1)
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NAME

6       SGEMV - performs one of the matrix-vector operations   y := alpha*A*x +
7       beta*y, or y := alpha*A'*x + beta*y,
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SYNOPSIS

10       SUBROUTINE SGEMV(TRANS,M,N,ALPHA,A,LDA,X,INCX,BETA,Y,INCY)
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12           REAL                                                   ALPHA,BETA
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14           INTEGER                                                INCX,INCY,LDA,M,N
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16           CHARACTER                                              TRANS
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18           REAL                                                   A(LDA,*),X(*),Y(*)
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PURPOSE

21       SGEMV  performs one of the matrix-vector operations
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23       where alpha and beta are scalars, x and y are vectors and A is an m  by
24       n matrix.
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ARGUMENTS

28       TRANS  - CHARACTER*1.
29              On  entry, TRANS specifies the operation to be performed as fol‐
30              lows:
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32              TRANS = 'N' or 'n'   y := alpha*A*x + beta*y.
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34              TRANS = 'T' or 't'   y := alpha*A'*x + beta*y.
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36              TRANS = 'C' or 'c'   y := alpha*A'*x + beta*y.
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38              Unchanged on exit.
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40       M      - INTEGER.
41              On entry, M specifies the number of rows of  the  matrix  A.   M
42              must be at least zero.  Unchanged on exit.
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44       N      - INTEGER.
45              On  entry, N specifies the number of columns of the matrix A.  N
46              must be at least zero.  Unchanged on exit.
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48       ALPHA  - REAL            .
49              On entry, ALPHA specifies the scalar alpha.  Unchanged on exit.
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51       A      - REAL             array of DIMENSION ( LDA, n ).
52              Before entry, the leading m by n part of the array A  must  con‐
53              tain the matrix of coefficients.  Unchanged on exit.
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55       LDA    - INTEGER.
56              On  entry, LDA specifies the first dimension of A as declared in
57              the calling (sub) program. LDA must be at least  max(  1,  m  ).
58              Unchanged on exit.
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60       X      - REAL             array of DIMENSION at least
61              (  1  +  (  n - 1 )*abs( INCX ) ) when TRANS = 'N' or 'n' and at
62              least ( 1 + ( m - 1 )*abs( INCX ) )  otherwise.   Before  entry,
63              the incremented array X must contain the vector x.  Unchanged on
64              exit.
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66       INCX   - INTEGER.
67              On entry, INCX specifies the increment for the  elements  of  X.
68              INCX must not be zero.  Unchanged on exit.
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70       BETA   - REAL            .
71              On  entry, BETA specifies the scalar beta. When BETA is supplied
72              as zero then Y need not be set on input.  Unchanged on exit.
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74       Y      - REAL             array of DIMENSION at least
75              ( 1 + ( m - 1 )*abs( INCY ) ) when TRANS = 'N'  or  'n'  and  at
76              least  (  1  +  ( n - 1 )*abs( INCY ) ) otherwise.  Before entry
77              with BETA non-zero, the incremented array  Y  must  contain  the
78              vector y. On exit, Y is overwritten by the updated vector y.
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80       INCY   - INTEGER.
81              On  entry,  INCY  specifies the increment for the elements of Y.
82              INCY must not be zero.  Unchanged on exit.
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FURTHER DETAILS

85       Level 2 Blas routine.
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87       -- Written on 22-October-1986.
88          Jack Dongarra, Argonne National Lab.
89          Jeremy Du Croz, Nag Central Office.
90          Sven Hammarling, Nag Central Office.
91          Richard Hanson, Sandia National Labs.
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96BLAS routine                     November 2008                        SGEMV(1)