CGESV(3)              LAPACK driver routine (version 3.1)             CGESV(3)



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

SYNOPSIS
       SUBROUTINE CGESV( N, NRHS, A, LDA, IPIV, B, LDB, INFO )

           INTEGER       INFO, LDA, LDB, N, NRHS

           INTEGER       IPIV( * )

           COMPLEX       A( LDA, * ), B( LDB, * )

PURPOSE
       CGESV computes the solution to a complex system of linear equations
          A * X = B, where A is an N-by-N matrix and X  and  B  are  N-by-NRHS
       matrices.

       The LU decomposition with partial pivoting and row interchanges is used
       to factor A as
          A = P * L * U,
       where P is a permutation matrix, L is unit lower triangular, and  U  is
       upper  triangular.   The  factored  form of A is then used to solve the
       system of equations A * X = B.


ARGUMENTS
       N       (input) INTEGER
               The number of linear equations, i.e., the order of  the  matrix
               A.  N >= 0.

       NRHS    (input) INTEGER
               The  number of right hand sides, i.e., the number of columns of
               the matrix B.  NRHS >= 0.

       A       (input/output) COMPLEX array, dimension (LDA,N)
               On entry, the N-by-N coefficient matrix A.  On exit,  the  fac-
               tors  L and U from the factorization A = P*L*U; the unit diago-
               nal elements of L are not stored.

       LDA     (input) INTEGER
               The leading dimension of the array A.  LDA >= max(1,N).

       IPIV    (output) INTEGER array, dimension (N)
               The pivot indices that define the permutation matrix P;  row  i
               of the matrix was interchanged with row IPIV(i).

       B       (input/output) COMPLEX array, dimension (LDB,NRHS)
               On entry, the N-by-NRHS matrix of right hand side matrix B.  On
               exit, if INFO = 0, the N-by-NRHS solution matrix X.

       LDB     (input) INTEGER
               The leading dimension of the array B.  LDB >= max(1,N).

       INFO    (output) INTEGER
               = 0:  successful exit
               < 0:  if INFO = -i, the i-th argument had an illegal value
               > 0:  if INFO = i, U(i,i) is exactly zero.   The  factorization
               has  been  completed,  but the factor U is exactly singular, so
               the solution could not be computed.



 LAPACK driver routine (version 3.N1o)vember 2006                        CGESV(3)