zgetri(3P) Sun Performance Library zgetri(3P)NAMEzgetri - compute the inverse of a matrix using the LU factorization
computed by ZGETRF
SYNOPSIS
SUBROUTINE ZGETRI(N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
DOUBLE COMPLEX A(LDA,*), WORK(*)
INTEGER N, LDA, LDWORK, INFO
INTEGER IPIVOT(*)
SUBROUTINE ZGETRI_64(N, A, LDA, IPIVOT, WORK, LDWORK, INFO)
DOUBLE COMPLEX A(LDA,*), WORK(*)
INTEGER*8 N, LDA, LDWORK, INFO
INTEGER*8 IPIVOT(*)
F95 INTERFACE
SUBROUTINE GETRI([N], A, [LDA], IPIVOT, [WORK], [LDWORK], [INFO])
COMPLEX(8), DIMENSION(:) :: WORK
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER :: N, LDA, LDWORK, INFO
INTEGER, DIMENSION(:) :: IPIVOT
SUBROUTINE GETRI_64([N], A, [LDA], IPIVOT, [WORK], [LDWORK], [INFO])
COMPLEX(8), DIMENSION(:) :: WORK
COMPLEX(8), DIMENSION(:,:) :: A
INTEGER(8) :: N, LDA, LDWORK, INFO
INTEGER(8), DIMENSION(:) :: IPIVOT
C INTERFACE
#include <sunperf.h>
void zgetri(int n, doublecomplex *a, int lda, int *ipivot, int *info);
void zgetri_64(long n, doublecomplex *a, long lda, long *ipivot, long
*info);
PURPOSEzgetri computes the inverse of a matrix using the LU factorization com‐
puted by ZGETRF.
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 ZGETRF. 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 ZGETRF; 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 zgetri(3P)
