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---
:name: dsytri2x
:md5sum: 683ca7b4f920246786909d9f75b2ce4b
:category: :subroutine
:arguments:
- uplo:
:type: char
:intent: input
- n:
:type: integer
:intent: input
- a:
:type: doublereal
:intent: input/output
:dims:
- lda
- n
- lda:
:type: integer
:intent: input
- ipiv:
:type: integer
:intent: input
:dims:
- n
- work:
:type: doublereal
:intent: workspace
:dims:
- n+nb+1
- nb+3
- nb:
:type: integer
:intent: input
- info:
:type: integer
:intent: output
:substitutions: {}
:fortran_help: " SUBROUTINE DSYTRI2X( UPLO, N, A, LDA, IPIV, WORK, NB, INFO )\n\n\
* Purpose\n\
* =======\n\
*\n\
* DSYTRI2X computes the inverse of a real symmetric indefinite matrix\n\
* A using the factorization A = U*D*U**T or A = L*D*L**T computed by\n\
* DSYTRF.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* UPLO (input) CHARACTER*1\n\
* Specifies whether the details of the factorization are stored\n\
* as an upper or lower triangular matrix.\n\
* = 'U': Upper triangular, form is A = U*D*U**T;\n\
* = 'L': Lower triangular, form is A = L*D*L**T.\n\
*\n\
* N (input) INTEGER\n\
* The order of the matrix A. N >= 0.\n\
*\n\
* A (input/output) DOUBLE PRECISION array, dimension (LDA,N)\n\
* On entry, the NNB diagonal matrix D and the multipliers\n\
* used to obtain the factor U or L as computed by DSYTRF.\n\
*\n\
* On exit, if INFO = 0, the (symmetric) inverse of the original\n\
* matrix. If UPLO = 'U', the upper triangular part of the\n\
* inverse is formed and the part of A below the diagonal is not\n\
* referenced; if UPLO = 'L' the lower triangular part of the\n\
* inverse is formed and the part of A above the diagonal is\n\
* not referenced.\n\
*\n\
* LDA (input) INTEGER\n\
* The leading dimension of the array A. LDA >= max(1,N).\n\
*\n\
* IPIV (input) INTEGER array, dimension (N)\n\
* Details of the interchanges and the NNB structure of D\n\
* as determined by DSYTRF.\n\
*\n\
* WORK (workspace) DOUBLE PRECISION array, dimension (N+NNB+1,NNB+3)\n\
*\n\
* NB (input) INTEGER\n\
* Block size\n\
*\n\
* INFO (output) INTEGER\n\
* = 0: successful exit\n\
* < 0: if INFO = -i, the i-th argument had an illegal value\n\
* > 0: if INFO = i, D(i,i) = 0; the matrix is singular and its\n\
* inverse could not be computed.\n\
*\n\n\
* =====================================================================\n\
*\n"
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