dgetri-f(3)

dgetri.f –

Synopsis

Functions/Subroutines

subroutine dgetri (N, A, LDA, IPIV, WORK, LWORK, INFO)
DGETRI

Function/Subroutine Documentation

subroutine dgetri (integerN, double precision, dimension( lda, * )A, integerLDA, integer, dimension( * )IPIV, double precision, dimension( * )WORK, integerLWORK, integerINFO)

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

 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.

Date:

November 2011

Definition at line 115 of file dgetri.f.

Author

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