sgesv (3p)

Name

sgesv - compute 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

Synopsis

SUBROUTINE SGESV(N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)

INTEGER N, NRHS, LDA, LDB, INFO
INTEGER IPIVOT(*)
REAL A(LDA,*), B(LDB,*)

SUBROUTINE SGESV_64(N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)

INTEGER*8 N, NRHS, LDA, LDB, INFO
INTEGER*8 IPIVOT(*)
REAL 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, 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, DIMENSION(:,:) :: A, B




C INTERFACE
#include <sunperf.h>

void sgesv(int n, int nrhs, float *a, int lda, int *ipivot,  float  *b,
int ldb, int *info);

void  sgesv_64(long  n,  long  nrhs,  float *a, long lda, long *ipivot,
float *b, long ldb, long *info);

Description

Oracle Solaris Studio Performance Library                            sgesv(3P)



NAME
       sgesv  -  compute  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


SYNOPSIS
       SUBROUTINE SGESV(N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)

       INTEGER N, NRHS, LDA, LDB, INFO
       INTEGER IPIVOT(*)
       REAL A(LDA,*), B(LDB,*)

       SUBROUTINE SGESV_64(N, NRHS, A, LDA, IPIVOT, B, LDB, INFO)

       INTEGER*8 N, NRHS, LDA, LDB, INFO
       INTEGER*8 IPIVOT(*)
       REAL 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, 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, DIMENSION(:,:) :: A, B




   C INTERFACE
       #include <sunperf.h>

       void sgesv(int n, int nrhs, float *a, int lda, int *ipivot,  float  *b,
                 int ldb, int *info);

       void  sgesv_64(long  n,  long  nrhs,  float *a, long lda, long *ipivot,
                 float *b, long ldb, long *info);



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.


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 fac-
                 tors L and U from the factorization A = P*L*U; the unit diag-
                 onal 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)
                 = 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.




                                  7 Nov 2015                         sgesv(3P)