---
name: "dgetri.f"
section: "3"
platform: "linux"
package: "lapack-doc"
version: "3.12.1-2"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/dgetri.f"
---

# dgetri.f(3)

## NAME

SRC/dgetri.f

## SYNOPSIS

### Functions/Subroutines

subroutine **dgetri** (n, a, lda, ipiv, work, lwork, info)\
 **DGETRI**

## Function/Subroutine Documentation

### 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.

Definition at line **113** of file **dgetri.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.