NAME

SYNOPSIS

  SUBROUTINE DGESV( N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)
  INTEGER N, NRHS, LDA, LDB, INFO
  INTEGER IPIVOT(*)
  DOUBLE PRECISION A(LDA,*), B(LDB,*)
 
  SUBROUTINE DGESV_64( N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)
  INTEGER*8 N, NRHS, LDA, LDB, INFO
  INTEGER*8 IPIVOT(*)
  DOUBLE PRECISION A(LDA,*), B(LDB,*)
 

F95 INTERFACE

  SUBROUTINE GESV( [N], [NRHS], A, [LDA], IPIVOT, B, [LDB], [INFO])
  INTEGER :: N, NRHS, LDA, LDB, INFO
  INTEGER, DIMENSION(:) :: IPIVOT
  REAL(8), DIMENSION(:,:) :: A, B
 
  SUBROUTINE GESV_64( [N], [NRHS], A, [LDA], IPIVOT, B, [LDB], [INFO])
  INTEGER(8) :: N, NRHS, LDA, LDB, INFO
  INTEGER(8), DIMENSION(:) :: IPIVOT
  REAL(8), DIMENSION(:,:) :: A, B
 

C INTERFACE

void dgesv(int n, int nrhs, double *a, int lda, int *ipivot, double *b, int ldb, int *info);

void dgesv_64(long n, long nrhs, double *a, long lda, long *ipivot, double *b, long ldb, long *info);

PURPOSE

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.

ARGUMENTS

* N (input)

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

* NRHS (input)

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

* A (input/output)

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 (input)

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

* IPIVOT (output)

The pivot indices that define the permutation matrix P; row i of the matrix was interchanged with row IPIVOT(i).

* B (input/output)

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 (input)

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

* INFO (output)