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---
:name: dgttrs
:md5sum: b93484e4a60657d1a7d75fd2575b68f7
:category: :subroutine
:arguments:
- trans:
:type: char
:intent: input
- n:
:type: integer
:intent: input
- nrhs:
:type: integer
:intent: input
- dl:
:type: doublereal
:intent: input
:dims:
- n-1
- d:
:type: doublereal
:intent: input
:dims:
- n
- du:
:type: doublereal
:intent: input
:dims:
- n-1
- du2:
:type: doublereal
:intent: input
:dims:
- n-2
- ipiv:
:type: integer
:intent: input
:dims:
- n
- b:
:type: doublereal
:intent: input/output
:dims:
- ldb
- nrhs
- ldb:
:type: integer
:intent: input
- info:
:type: integer
:intent: output
:substitutions: {}
:fortran_help: " SUBROUTINE DGTTRS( TRANS, N, NRHS, DL, D, DU, DU2, IPIV, B, LDB, INFO )\n\n\
* Purpose\n\
* =======\n\
*\n\
* DGTTRS solves one of the systems of equations\n\
* A*X = B or A'*X = B,\n\
* with a tridiagonal matrix A using the LU factorization computed\n\
* by DGTTRF.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* TRANS (input) CHARACTER*1\n\
* Specifies the form of the system of equations.\n\
* = 'N': A * X = B (No transpose)\n\
* = 'T': A'* X = B (Transpose)\n\
* = 'C': A'* X = B (Conjugate transpose = Transpose)\n\
*\n\
* N (input) INTEGER\n\
* The order of the matrix A.\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\
* DL (input) DOUBLE PRECISION array, dimension (N-1)\n\
* The (n-1) multipliers that define the matrix L from the\n\
* LU factorization of A.\n\
*\n\
* D (input) DOUBLE PRECISION array, dimension (N)\n\
* The n diagonal elements of the upper triangular matrix U from\n\
* the LU factorization of A.\n\
*\n\
* DU (input) DOUBLE PRECISION array, dimension (N-1)\n\
* The (n-1) elements of the first super-diagonal of U.\n\
*\n\
* DU2 (input) DOUBLE PRECISION array, dimension (N-2)\n\
* The (n-2) elements of the second super-diagonal of U.\n\
*\n\
* IPIV (input) INTEGER array, dimension (N)\n\
* The pivot indices; for 1 <= i <= n, row i of the matrix was\n\
* interchanged with row IPIV(i). IPIV(i) will always be either\n\
* i or i+1; IPIV(i) = i indicates a row interchange was not\n\
* required.\n\
*\n\
* B (input/output) DOUBLE PRECISION array, dimension (LDB,NRHS)\n\
* On entry, the matrix of right hand side vectors B.\n\
* On exit, B is overwritten by 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 = -i, the i-th argument had an illegal value\n\
*\n\n\
* =====================================================================\n\
*\n\
* .. Local Scalars ..\n LOGICAL NOTRAN\n INTEGER ITRANS, J, JB, NB\n\
* ..\n\
* .. External Functions ..\n INTEGER ILAENV\n EXTERNAL ILAENV\n\
* ..\n\
* .. External Subroutines ..\n EXTERNAL DGTTS2, XERBLA\n\
* ..\n\
* .. Intrinsic Functions ..\n INTRINSIC MAX, MIN\n\
* ..\n"
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