sgesv.f man page

sgesv.f —

Synopsis

Functions/Subroutines

subroutine sgesv (N, NRHS, A, LDA, IPIV, B, LDB, INFO)
SGESV computes the solution to system of linear equations A * X = B for GE matrices (simple driver)

Function/Subroutine Documentation

subroutine sgesv (integerN, integerNRHS, real, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, real, dimension( ldb, * )B, integerLDB, integerINFO)

SGESV computes the solution to system of linear equations A * X = B for GE matrices (simple driver)  

Purpose:

 SGESV computes the solution to a real system of linear equations
    A * X = B,
 where A is an N-by-N matrix and X and B are N-by-NRHS matrices.

 The LU decomposition with partial pivoting and row interchanges is
 used to factor A as
    A = P * L * U,
 where P is a permutation matrix, L is unit lower triangular, and U is
 upper triangular.  The factored form of A is then used to solve the
 system of equations A * X = B.
Parameters:

N

          N is INTEGER
          The number of linear equations, i.e., the order of the
          matrix A.  N >= 0.

NRHS

          NRHS is INTEGER
          The number of right hand sides, i.e., the number of columns
          of the matrix B.  NRHS >= 0.

A

          A is REAL array, dimension (LDA,N)
          On entry, the N-by-N coefficient matrix A.
          On exit, the factors L and U from the factorization
          A = P*L*U; the unit diagonal elements of L are not stored.

LDA

          LDA is INTEGER
          The leading dimension of the array A.  LDA >= max(1,N).

IPIV

          IPIV is INTEGER array, dimension (N)
          The pivot indices that define the permutation matrix P;
          row i of the matrix was interchanged with row IPIV(i).

B

          B is REAL array, dimension (LDB,NRHS)
          On entry, the N-by-NRHS matrix of right hand side matrix B.
          On exit, if INFO = 0, the N-by-NRHS solution matrix X.

LDB

          LDB is INTEGER
          The leading dimension of the array B.  LDB >= max(1,N).

INFO

          INFO is INTEGER
          = 0:  successful exit
          < 0:  if INFO = -i, the i-th argument had an illegal value
          > 0:  if INFO = i, U(i,i) is exactly zero.  The factorization
                has been completed, but the factor U is exactly
                singular, so the solution could not be computed.
Author:

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Date:

November 2011

Definition at line 123 of file sgesv.f.

Author

Generated automatically by Doxygen for LAPACK from the source code.

Referenced By

sgesv(3) is an alias of sgesv.f(3).

Sat Nov 16 2013 Version 3.4.2 LAPACK