**?gels**
uses *QR* or *LQ* factorization to solve an overdetermined or underdetermined linear system with a full rank matrix.

```
call sgels (
```

*trans, m, n, nrhs, a, lda, b, ldb, work, lwork, info*)

call dgels (*trans, m, n, nrhs, a, lda, b, ldb, work, lwork, info*)

call cgels (*trans, m, n, nrhs, a, lda, b, ldb, work, lwork, info*)

call zgels (*trans, m, n, nrhs, a, lda, b, ldb, work, lwork, info*)

**?gelsy**
computes the minimum-norm solution to a linear least squares problem using a complete orthogonal factorization of *A*.

```
call sgelsy (
```

*m, n, nrhs, a, lda, b, ldb, jpvt, rcond, rank, work,
lwork, info*)

call dgelsy (*m, n, nrhs, a, lda, b, ldb, jpvt, rcond, rank, work,
lwork, info*)

call cgelsy (*m, n, nrhs, a, lda, b, ldb, jpvt, rcond, rank, work,
lwork, rwork, info*)

call zgelsy (*m, n, nrhs, a, lda, b, ldb, jpvt, rcond, rank, work,
lwork, rwork, info*)

**?gelss**
computes the minimum-norm solution to a linear least squares problem using the singular value decomposition of *A*.

```
call sgelss (
```

*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, info*)

call dgelss (*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, info*)

call cgelss (*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, rwork, info*)

call zgelss (*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, rwork, info*)

**?gelsd**
computes the minimum-norm solution to a linear least squares problem using the singular value decomposition of *A* and a divide and conquer method.

```
call sgelsd (
```

*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, iwork, info*)

call dgelsd (*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, iwork, info*)

call cgelsd (*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, rwork, iwork, info*)

call zgelsd (*m, n, nrhs, a, lda, b, ldb, s, rcond, rank, work,
lwork, rwork, iwork, info*)

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