dgetri(3P) Sun Performance Library dgetri(3P)NAMEdgetri - compute the inverse of a matrix using the LU factorization
computed by DGETRF
SYNOPSIS
SUBROUTINE DGETRI(N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
INTEGER N, LDA, LDWORK, INFO
INTEGER IPIVOT(*)
DOUBLE PRECISION A(LDA,*), WORK(*)
SUBROUTINE DGETRI_64(N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
INTEGER*8 N, LDA, LDWORK, INFO
INTEGER*8 IPIVOT(*)
DOUBLE PRECISION A(LDA,*), WORK(*)
F95 INTERFACE
SUBROUTINE GETRI([N], A, [LDA], IPIVOT, [WORK], [LDWORK], [INFO])
INTEGER :: N, LDA, LDWORK, INFO
INTEGER, DIMENSION(:) :: IPIVOT
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:) :: A
SUBROUTINE GETRI_64([N], A, [LDA], IPIVOT, [WORK], [LDWORK], [INFO])
INTEGER(8) :: N, LDA, LDWORK, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT
REAL(8), DIMENSION(:) :: WORK
REAL(8), DIMENSION(:,:) :: A
C INTERFACE
#include <sunperf.h>
void dgetri(int n, double *a, int lda, int *ipivot, int *info);
void dgetri_64(long n, double *a, long lda, long *ipivot, long *info);
PURPOSEdgetri computes the inverse of a matrix using the LU factorization com‐
puted by DGETRF.
This method inverts U and then computes inv(A) by solving the system
inv(A)*L = inv(U) for inv(A).
ARGUMENTS
N (input) The order of the matrix A. N >= 0.
A (input/output)
On entry, the factors L and U from the factorization A =
P*L*U as computed by DGETRF. On exit, if INFO = 0, the
inverse of the original matrix A.
LDA (input)
The leading dimension of the array A. LDA >= max(1,N).
IPIVOT (input)
The pivot indices from DGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIVOT(i).
WORK (workspace)
On exit, if INFO=0, then WORK(1) returns the optimal LDWORK.
LDWORK (input)
The dimension of the array WORK. LDWORK >= max(1,N). For
optimal performance LDWORK >= N*NB, where NB is the optimal
blocksize returned by ILAENV.
If LDWORK = -1, then a workspace query is assumed; the rou‐
tine only calculates the optimal size of the WORK array,
returns this value as the first entry of the WORK array, and
no error message related to LDWORK is issued by XERBLA.
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 matrix is sin‐
gular and its inverse could not be computed.
6 Mar 2009 dgetri(3P)