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

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

10       SUBROUTINE ZPOSV( UPLO, N, NRHS, A, LDA, B, LDB, INFO )
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12           CHARACTER     UPLO
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14           INTEGER       INFO, LDA, LDB, N, NRHS
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16           COMPLEX*16    A( LDA, * ), B( LDB, * )
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PURPOSE

19       ZPOSV computes the solution to a complex system of linear equations
20          A * X = B, where A is an N-by-N Hermitian positive  definite  matrix
21       and X and B are N-by-NRHS matrices.
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23       The Cholesky decomposition is used to factor A as
24          A = U**H* U,  if UPLO = 'U', or
25          A = L * L**H,  if UPLO = 'L',
26       where  U  is  an  upper  triangular matrix and  L is a lower triangular
27       matrix.  The factored form of A is then used to  solve  the  system  of
28       equations A * X = B.
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ARGUMENTS

32       UPLO    (input) CHARACTER*1
33               = 'U':  Upper triangle of A is stored;
34               = 'L':  Lower triangle of A is stored.
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36       N       (input) INTEGER
37               The  number  of linear equations, i.e., the order of the matrix
38               A.  N >= 0.
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40       NRHS    (input) INTEGER
41               The number of right hand sides, i.e., the number of columns  of
42               the matrix B.  NRHS >= 0.
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44       A       (input/output) COMPLEX*16 array, dimension (LDA,N)
45               On  entry,  the Hermitian matrix A.  If UPLO = 'U', the leading
46               N-by-N upper triangular part of A contains the upper triangular
47               part of the matrix A, and the strictly lower triangular part of
48               A is not referenced.  If UPLO = 'L', the leading  N-by-N  lower
49               triangular  part of A contains the lower triangular part of the
50               matrix A, and the strictly upper triangular part of  A  is  not
51               referenced.
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53               On  exit, if INFO = 0, the factor U or L from the Cholesky fac‐
54               torization A = U**H*U or A = L*L**H.
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56       LDA     (input) INTEGER
57               The leading dimension of the array A.  LDA >= max(1,N).
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59       B       (input/output) COMPLEX*16 array, dimension (LDB,NRHS)
60               On entry, the N-by-NRHS right hand side matrix B.  On exit,  if
61               INFO = 0, the N-by-NRHS solution matrix X.
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63       LDB     (input) INTEGER
64               The leading dimension of the array B.  LDB >= max(1,N).
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66       INFO    (output) INTEGER
67               = 0:  successful exit
68               < 0:  if INFO = -i, the i-th argument had an illegal value
69               >  0:   if  INFO  = i, the leading minor of order i of A is not
70               positive definite, so the factorization could not be completed,
71               and the solution has not been computed.
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75 LAPACK driver routine (version 3.N1o)vember 2006                        ZPOSV(1)
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