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---
:name: dpttrs
:md5sum: 4df62154d25e780b1accac29911e5aef
:category: :subroutine
:arguments:
- n:
:type: integer
:intent: input
- nrhs:
:type: integer
:intent: input
- d:
:type: doublereal
:intent: input
:dims:
- n
- e:
:type: doublereal
:intent: input
:dims:
- n-1
- b:
:type: doublereal
:intent: input/output
:dims:
- ldb
- nrhs
- ldb:
:type: integer
:intent: input
- info:
:type: integer
:intent: output
:substitutions: {}
:fortran_help: " SUBROUTINE DPTTRS( N, NRHS, D, E, B, LDB, INFO )\n\n\
* Purpose\n\
* =======\n\
*\n\
* DPTTRS solves a tridiagonal system of the form\n\
* A * X = B\n\
* using the L*D*L' factorization of A computed by DPTTRF. D is a\n\
* diagonal matrix specified in the vector D, L is a unit bidiagonal\n\
* matrix whose subdiagonal is specified in the vector E, and X and B\n\
* are N by NRHS matrices.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* N (input) INTEGER\n\
* The order of the tridiagonal matrix A. N >= 0.\n\
*\n\
* NRHS (input) INTEGER\n\
* The number of right hand sides, i.e., the number of columns\n\
* of the matrix B. NRHS >= 0.\n\
*\n\
* D (input) DOUBLE PRECISION array, dimension (N)\n\
* The n diagonal elements of the diagonal matrix D from the\n\
* L*D*L' factorization of A.\n\
*\n\
* E (input) DOUBLE PRECISION array, dimension (N-1)\n\
* The (n-1) subdiagonal elements of the unit bidiagonal factor\n\
* L from the L*D*L' factorization of A. E can also be regarded\n\
* as the superdiagonal of the unit bidiagonal factor U from the\n\
* factorization A = U'*D*U.\n\
*\n\
* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)\n\
* On entry, the right hand side vectors B for the system of\n\
* linear equations.\n\
* On exit, the solution vectors, X.\n\
*\n\
* LDB (input) INTEGER\n\
* The leading dimension of the array B. LDB >= max(1,N).\n\
*\n\
* INFO (output) INTEGER\n\
* = 0: successful exit\n\
* < 0: if INFO = -k, the k-th argument had an illegal value\n\
*\n\n\
* =====================================================================\n\
*\n\
* .. Local Scalars ..\n INTEGER J, JB, NB\n\
* ..\n\
* .. External Functions ..\n INTEGER ILAENV\n EXTERNAL ILAENV\n\
* ..\n\
* .. External Subroutines ..\n EXTERNAL DPTTS2, XERBLA\n\
* ..\n\
* .. Intrinsic Functions ..\n INTRINSIC MAX, MIN\n\
* ..\n"
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