**p?gehrd**
reduces a general matrix to upper Hessenberg form.

```
call psgehrd (
```

*n, ilo, ihi, a, ia, ja, desca, tau, work, lwork, info*)

call pdgehrd (*n, ilo, ihi, a, ia, ja, desca, tau, work, lwork, info*)

call pcgehrd (*n, ilo, ihi, a, ia, ja, desca, tau, work, lwork, info*)

call pzgehrd (*n, ilo, ihi, a, ia, ja, desca, tau, work, lwork, info*)

**p?ormhr**
multiplies a general matrix by the orthogonal transformation matrix from a reduction to Hessenberg form determined by
p?gehrd.

```
call psormhr (
```

*side, trans, m, n, ilo, ihi, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info*)

call pdormhr (*side, trans, m, n, ilo, ihi, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info*)

**p?unmhr**
multiplies a general matrix by the unitary transformation matrix from a reduction to Hessenberg form determined by
p?gehrd.

```
call pcunmhr (
```

*side, trans, m, n, ilo, ihi, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info*)

call pzunmhr (*side, trans, m, n, ilo, ihi, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info*)

**p?lahqr**
computes the Schur decomposition and/or eigenvalues of a matrix already in Hessenberg form.

```
call pslahqr (
```

*wantt, wantz, n, ilo, ihi, a, desca, wr, wi, iloz, ihiz, z, descz, work, lwork, iwork, ilwork, info*)

call pdlahqr (*wantt, wantz, n, ilo, ihi, a, desca, wr, wi, iloz, ihiz, z, descz, work, lwork, iwork, ilwork, info*)

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