Man page - getri(3)

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Manual

getri

NAME
SYNOPSIS
Functions
Detailed Description
Function Documentation
subroutine cgetri (integer n, complex, dimension( lda, * ) a, integer lda,integer, dimension( * ) ipiv, complex, dimension( * ) work, integerlwork, integer info)
subroutine dgetri (integer n, double precision, dimension( lda, * ) a,integer lda, integer, dimension( * ) ipiv, double precision, dimension(* ) work, integer lwork, integer info)
subroutine sgetri (integer n, real, dimension( lda, * ) a, integer lda,integer, dimension( * ) ipiv, real, dimension( * ) work, integer lwork,integer info)
subroutine zgetri (integer n, complex*16, dimension( lda, * ) a, integerlda, integer, dimension( * ) ipiv, complex*16, dimension( * ) work,integer lwork, integer info)
Author

NAME

getri - getri: triangular inverse

SYNOPSIS

Functions

subroutine cgetri (n, a, lda, ipiv, work, lwork, info)
CGETRI
subroutine dgetri (n, a, lda, ipiv, work, lwork, info)
DGETRI
subroutine sgetri (n, a, lda, ipiv, work, lwork, info)
SGETRI
subroutine zgetri (n, a, lda, ipiv, work, lwork, info)
ZGETRI

Detailed Description

Function Documentation

subroutine cgetri (integer n, complex, dimension( lda, * ) a, integer lda,integer, dimension( * ) ipiv, complex, dimension( * ) work, integerlwork, integer info)

CGETRI

Purpose:

CGETRI computes the inverse of a matrix using the LU factorization
computed by CGETRF.

This method inverts U and then computes inv(A) by solving the system
inv(A)*L = inv(U) for inv(A).

Parameters

N

N is INTEGER
The order of the matrix A. N >= 0.

A

A is COMPLEX array, dimension (LDA,N)
On entry, the factors L and U from the factorization
A = P*L*U as computed by CGETRF.
On exit, if INFO = 0, the inverse of the original matrix A.

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 from CGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIV(i).

WORK

WORK is COMPLEX array, dimension (MAX(1,LWORK))
On exit, if INFO=0, then WORK(1) returns the optimal LWORK.

LWORK

LWORK is INTEGER
The dimension of the array WORK. LWORK >= max(1,N).
For optimal performance LWORK >= N*NB, where NB is
the optimal blocksize returned by ILAENV.

If LWORK = -1, then a workspace query is assumed; the routine
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 LWORK is issued by XERBLA.

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 matrix is
singular and its inverse could not be computed.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine dgetri (integer n, double precision, dimension( lda, * ) a,integer lda, integer, dimension( * ) ipiv, double precision, dimension(* ) work, integer lwork, integer info)

DGETRI

Purpose:

DGETRI computes the inverse of a matrix using the LU factorization
computed by DGETRF.

This method inverts U and then computes inv(A) by solving the system
inv(A)*L = inv(U) for inv(A).

Parameters

N

N is INTEGER
The order of the matrix A. N >= 0.

A

A is DOUBLE PRECISION array, dimension (LDA,N)
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

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

IPIV

IPIV is INTEGER array, dimension (N)
The pivot indices from DGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIV(i).

WORK

WORK is DOUBLE PRECISION array, dimension (MAX(1,LWORK))
On exit, if INFO=0, then WORK(1) returns the optimal LWORK.

LWORK

LWORK is INTEGER
The dimension of the array WORK. LWORK >= max(1,N).
For optimal performance LWORK >= N*NB, where NB is
the optimal blocksize returned by ILAENV.

If LWORK = -1, then a workspace query is assumed; the routine
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 LWORK is issued by XERBLA.

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 matrix is
singular and its inverse could not be computed.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine sgetri (integer n, real, dimension( lda, * ) a, integer lda,integer, dimension( * ) ipiv, real, dimension( * ) work, integer lwork,integer info)

SGETRI

Purpose:

SGETRI computes the inverse of a matrix using the LU factorization
computed by SGETRF.

This method inverts U and then computes inv(A) by solving the system
inv(A)*L = inv(U) for inv(A).

Parameters

N

N is INTEGER
The order of the matrix A. N >= 0.

A

A is REAL array, dimension (LDA,N)
On entry, the factors L and U from the factorization
A = P*L*U as computed by SGETRF.
On exit, if INFO = 0, the inverse of the original matrix A.

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 from SGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIV(i).

WORK

WORK is REAL array, dimension (MAX(1,LWORK))
On exit, if INFO=0, then WORK(1) returns the optimal LWORK.

LWORK

LWORK is INTEGER
The dimension of the array WORK. LWORK >= max(1,N).
For optimal performance LWORK >= N*NB, where NB is
the optimal blocksize returned by ILAENV.

If LWORK = -1, then a workspace query is assumed; the routine
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 LWORK is issued by XERBLA.

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 matrix is
singular and its inverse could not be computed.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

subroutine zgetri (integer n, complex*16, dimension( lda, * ) a, integerlda, integer, dimension( * ) ipiv, complex*16, dimension( * ) work,integer lwork, integer info)

ZGETRI

Purpose:

ZGETRI computes the inverse of a matrix using the LU factorization
computed by ZGETRF.

This method inverts U and then computes inv(A) by solving the system
inv(A)*L = inv(U) for inv(A).

Parameters

N

N is INTEGER
The order of the matrix A. N >= 0.

A

A is COMPLEX*16 array, dimension (LDA,N)
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

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

IPIV

IPIV is INTEGER array, dimension (N)
The pivot indices from ZGETRF; for 1<=i<=N, row i of the
matrix was interchanged with row IPIV(i).

WORK

WORK is COMPLEX*16 array, dimension (MAX(1,LWORK))
On exit, if INFO=0, then WORK(1) returns the optimal LWORK.

LWORK

LWORK is INTEGER
The dimension of the array WORK. LWORK >= max(1,N).
For optimal performance LWORK >= N*NB, where NB is
the optimal blocksize returned by ILAENV.

If LWORK = -1, then a workspace query is assumed; the routine
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 LWORK is issued by XERBLA.

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 matrix is
singular and its inverse could not be computed.

Author

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Author

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