1CGESV(1)              LAPACK driver routine (version 3.1)             CGESV(1)
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NAME

6       CGESV  -  the solution to a complex system of linear equations  A * X =
7       B,
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SYNOPSIS

10       SUBROUTINE CGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )
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12           INTEGER       INFO, LDA, LDB, N, NRHS
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14           INTEGER       IPIV( * )
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16           COMPLEX       A( LDA, * ), B( LDB, * )
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PURPOSE

19       CGESV computes the solution to a complex system of linear equations
20          A * X = B, where A is an N-by-N matrix and X  and  B  are  N-by-NRHS
21       matrices.
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23       The LU decomposition with partial pivoting and row interchanges is used
24       to factor A as
25          A = P * L * U,
26       where P is a permutation matrix, L is unit lower triangular, and  U  is
27       upper  triangular.   The  factored  form of A is then used to solve the
28       system of equations A * X = B.
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ARGUMENTS

32       N       (input) INTEGER
33               The number of linear equations, i.e., the order of  the  matrix
34               A.  N >= 0.
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36       NRHS    (input) INTEGER
37               The  number of right hand sides, i.e., the number of columns of
38               the matrix B.  NRHS >= 0.
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40       A       (input/output) COMPLEX array, dimension (LDA,N)
41               On entry, the N-by-N coefficient matrix A.  On exit,  the  fac‐
42               tors  L and U from the factorization A = P*L*U; the unit diago‐
43               nal elements of L are not stored.
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45       LDA     (input) INTEGER
46               The leading dimension of the array A.  LDA >= max(1,N).
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48       IPIV    (output) INTEGER array, dimension (N)
49               The pivot indices that define the permutation matrix P;  row  i
50               of the matrix was interchanged with row IPIV(i).
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52       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
53               On entry, the N-by-NRHS matrix of right hand side matrix B.  On
54               exit, if INFO = 0, the N-by-NRHS solution matrix X.
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56       LDB     (input) INTEGER
57               The leading dimension of the array B.  LDB >= max(1,N).
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59       INFO    (output) INTEGER
60               = 0:  successful exit
61               < 0:  if INFO = -i, the i-th argument had an illegal value
62               > 0:  if INFO = i, U(i,i) is exactly zero.   The  factorization
63               has  been  completed,  but the factor U is exactly singular, so
64               the solution could not be computed.
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68 LAPACK driver routine (version 3.N1o)vember 2006                        CGESV(1)