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---
:name: sgtsv
:md5sum: d0c8275ef5b870545d926bfab7aac31d
:category: :subroutine
:arguments:
- n:
:type: integer
:intent: input
- nrhs:
:type: integer
:intent: input
- dl:
:type: real
:intent: input/output
:dims:
- n-1
- d:
:type: real
:intent: input/output
:dims:
- n
- du:
:type: real
:intent: input/output
:dims:
- n-1
- b:
:type: real
:intent: input/output
:dims:
- ldb
- nrhs
- ldb:
:type: integer
:intent: input
- info:
:type: integer
:intent: output
:substitutions: {}
:fortran_help: " SUBROUTINE SGTSV( N, NRHS, DL, D, DU, B, LDB, INFO )\n\n\
* Purpose\n\
* =======\n\
*\n\
* SGTSV solves the equation\n\
*\n\
* A*X = B,\n\
*\n\
* where A is an n by n tridiagonal matrix, by Gaussian elimination with\n\
* partial pivoting.\n\
*\n\
* Note that the equation A'*X = B may be solved by interchanging the\n\
* order of the arguments DU and DL.\n\
*\n\n\
* Arguments\n\
* =========\n\
*\n\
* N (input) INTEGER\n\
* The order of the 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\
* DL (input/output) REAL array, dimension (N-1)\n\
* On entry, DL must contain the (n-1) sub-diagonal elements of\n\
* A.\n\
*\n\
* On exit, DL is overwritten by the (n-2) elements of the\n\
* second super-diagonal of the upper triangular matrix U from\n\
* the LU factorization of A, in DL(1), ..., DL(n-2).\n\
*\n\
* D (input/output) REAL array, dimension (N)\n\
* On entry, D must contain the diagonal elements of A.\n\
*\n\
* On exit, D is overwritten by the n diagonal elements of U.\n\
*\n\
* DU (input/output) REAL array, dimension (N-1)\n\
* On entry, DU must contain the (n-1) super-diagonal elements\n\
* of A.\n\
*\n\
* On exit, DU is overwritten by the (n-1) elements of the first\n\
* super-diagonal of U.\n\
*\n\
* B (input/output) REAL array, dimension (LDB,NRHS)\n\
* On entry, the N by NRHS matrix of right hand side matrix B.\n\
* On exit, if INFO = 0, the N by NRHS solution matrix 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\
* > 0: if INFO = i, U(i,i) is exactly zero, and the solution\n\
* has not been computed. The factorization has not been\n\
* completed unless i = N.\n\
*\n\n\
* =====================================================================\n\
*\n"
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