1CSPTRI(1)                LAPACK routine (version 3.2)                CSPTRI(1)
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NAME

6       CSPTRI  - computes the inverse of a complex symmetric indefinite matrix
7       A in packed storage using  the  factorization  A  =  U*D*U**T  or  A  =
8       L*D*L**T computed by CSPTRF
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SYNOPSIS

11       SUBROUTINE CSPTRI( UPLO, N, AP, IPIV, WORK, INFO )
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13           CHARACTER      UPLO
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15           INTEGER        INFO, N
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17           INTEGER        IPIV( * )
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19           COMPLEX        AP( * ), WORK( * )
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PURPOSE

22       CSPTRI  computes the inverse of a complex symmetric indefinite matrix A
23       in packed storage using the factorization A = U*D*U**T or A =  L*D*L**T
24       computed by CSPTRF.
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ARGUMENTS

27       UPLO    (input) CHARACTER*1
28               Specifies  whether  the details of the factorization are stored
29               as an upper or lower triangular matrix.  = 'U':  Upper triangu‐
30               lar, form is A = U*D*U**T;
31               = 'L':  Lower triangular, form is A = L*D*L**T.
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33       N       (input) INTEGER
34               The order of the matrix A.  N >= 0.
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36       AP      (input/output) COMPLEX array, dimension (N*(N+1)/2)
37               On  entry, the block diagonal matrix D and the multipliers used
38               to obtain the factor U or L as computed by CSPTRF, stored as  a
39               packed  triangular  matrix.  On exit, if INFO = 0, the (symmet‐
40               ric) inverse of the original matrix, stored as a packed  trian‐
41               gular  matrix. The j-th column of inv(A) is stored in the array
42               AP as follows: if UPLO = 'U', AP(i + (j-1)*j/2)  =  inv(A)(i,j)
43               for   1<=i<=j;   if  UPLO  =  'L',  AP(i  +  (j-1)*(2n-j)/2)  =
44               inv(A)(i,j) for j<=i<=n.
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46       IPIV    (input) INTEGER array, dimension (N)
47               Details of the interchanges and the block  structure  of  D  as
48               determined by CSPTRF.
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50       WORK    (workspace) COMPLEX array, dimension (N)
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52       INFO    (output) INTEGER
53               = 0: successful exit
54               < 0: if INFO = -i, the i-th argument had an illegal value
55               >  0:  if  INFO = i, D(i,i) = 0; the matrix is singular and its
56               inverse could not be computed.
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60 LAPACK routine (version 3.2)    November 2008                       CSPTRI(1)
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