---
name: "dorg2l"
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/dorg2l.f"
---

# dorg2l(3)

Part of [dorg2l.f(3)](/dorg2l.f/3.md).

## NAME

SRC/dorg2l.f

## SYNOPSIS

### Functions/Subroutines

subroutine **dorg2l** (m, n, k, a, lda, tau, work, info)\
 **DORG2L** generates all or part of the orthogonal matrix Q from a QL factorization determined by sgeqlf (unblocked algorithm).

## Function/Subroutine Documentation

### subroutine dorg2l (integer m, integer n, integer k, double precision, dimension( lda, \* ) a, integer lda, double precision, dimension( \* ) tau, double precision, dimension( \* ) work, integer info)

**DORG2L** generates all or part of the orthogonal matrix Q from a QL factorization determined by sgeqlf (unblocked algorithm).

**Purpose:**

```
!>
!> DORG2L generates an m by n real matrix Q with orthonormal columns,
!> which is defined as the last n columns of a product of k elementary
!> reflectors of order m
!>
!>       Q  =  H(k) . . . H(2) H(1)
!>
!> as returned by DGEQLF.
!>
```

**Parameters**

*M*

```
!>          M is INTEGER
!>          The number of rows of the matrix Q. M >= 0.
!>
```

*N*

```
!>          N is INTEGER
!>          The number of columns of the matrix Q. M >= N >= 0.
!>
```

*K*

```
!>          K is INTEGER
!>          The number of elementary reflectors whose product defines the
!>          matrix Q. N >= K >= 0.
!>
```

*A*

```
!>          A is DOUBLE PRECISION array, dimension (LDA,N)
!>          On entry, the (n-k+i)-th column must contain the vector which
!>          defines the elementary reflector H(i), for i = 1,2,...,k, as
!>          returned by DGEQLF in the last k columns of its array
!>          argument A.
!>          On exit, the m by n matrix Q.
!>
```

*LDA*

```
!>          LDA is INTEGER
!>          The first dimension of the array A. LDA >= max(1,M).
!>
```

*TAU*

```
!>          TAU is DOUBLE PRECISION array, dimension (K)
!>          TAU(i) must contain the scalar factor of the elementary
!>          reflector H(i), as returned by DGEQLF.
!>
```

*WORK*

```
!>          WORK is DOUBLE PRECISION array, dimension (N)
!>
```

*INFO*

```
!>          INFO is INTEGER
!>          = 0: successful exit
!>          < 0: if INFO = -i, the i-th argument has an illegal value
!>
```

**Author**

Univ. of Tennessee

Univ. of California Berkeley

Univ. of Colorado Denver

NAG Ltd.

Definition at line **113** of file **dorg2l.f**.

## Author

Generated automatically by Doxygen for LAPACK from the source code.