1CSPTRI(1)                LAPACK routine (version 3.1)                CSPTRI(1)
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NAME

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

28       UPLO    (input) CHARACTER*1
29               Specifies  whether  the details of the factorization are stored
30               as an upper or lower triangular matrix.  = 'U':  Upper triangu‐
31               lar, form is A = U*D*U**T;
32               = 'L':  Lower triangular, form is A = L*D*L**T.
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34       N       (input) INTEGER
35               The order of the matrix A.  N >= 0.
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37       AP      (input/output) COMPLEX array, dimension (N*(N+1)/2)
38               On  entry, the block diagonal matrix D and the multipliers used
39               to obtain the factor U or L as computed by CSPTRF, stored as  a
40               packed triangular matrix.
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42               On  exit,  if INFO = 0, the (symmetric) inverse of the original
43               matrix, stored as a packed triangular matrix. The  j-th  column
44               of  inv(A) is stored in the array AP as follows: if UPLO = 'U',
45               AP(i + (j-1)*j/2) = inv(A)(i,j) for 1<=i<=j;  if  UPLO  =  'L',
46               AP(i + (j-1)*(2n-j)/2) = inv(A)(i,j) for j<=i<=n.
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48       IPIV    (input) INTEGER array, dimension (N)
49               Details  of  the  interchanges  and the block structure of D as
50               determined by CSPTRF.
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52       WORK    (workspace) COMPLEX array, dimension (N)
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54       INFO    (output) INTEGER
55               = 0: successful exit
56               < 0: if INFO = -i, the i-th argument had an illegal value
57               > 0: if INFO = i, D(i,i) = 0; the matrix is  singular  and  its
58               inverse could not be computed.
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62 LAPACK routine (version 3.1)    November 2006                       CSPTRI(1)
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