### Symmetric Eigenvalue Problems

p?sytrd reduces a symmetric matrix to real symmetric tridiagonal form by an orthogonal similarity transformation.
``` call pssytrd (uplo, n, a, ia, ja, desca, d, e, tau, work, lwork, info) call pdsytrd (uplo, n, a, ia, ja, desca, d, e, tau, work, lwork, info) ```

p?ormtr multiplies a general matrix by the orthogonal transformation matrix from a reduction to tridiagonal form determined by p?sytrd.
``` call psormtr (side, uplo, trans, m, n, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info) call pdormtr (side, uplo, trans, m, n, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info) ```

p?hetrd reduces a Hermitian matrix to Hermitian tridiagonal form by a unitary similarity transformation.
``` call pchetrd (uplo, n, a, ia, ja, desca, d, e, tau, work, lwork, info) call pzhetrd (uplo, n, a, ia, ja, desca, d, e, tau, work, lwork, info) ```

p?unmtr multiplies a general matrix by the unitary transformation matrix from a reduction to tridiagonal form determined by p?hetrd.
``` call pcunmtr (side, uplo, trans, m, n, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info) call pzunmtr (side, uplo, trans, m, n, a, ia, ja, desca, tau, c, ic, jc, descc, work, lwork, info) ```

p?stebz computes the eigenvalues of a symmetric tridiagonal matrix by bisection.
``` call psstebz (ictxt, range, order, n, vl, vu, il, iu, abstol, d, e, m, nsplit, w, iblock, isplit, w, iblock, work, iwork, liwork, info) call pdstebz (ictxt, range, order, n, vl, vu, il, iu, abstol, d, e, m, nsplit, w, iblock, isplit, w, iblock, work, iwork, liwork, info) ```

p?stein computes the eigenvectors of a tridiagonal matrix using inverse iteration.
``` call psstein (n, d, e, m, w, iblock, isplit, orfac, z, iz, jz, descz, work, lwork, iwork, liwork, ifailv, iclustr, gap, info) call pdstein (n, d, e, m, w, iblock, isplit, orfac, z, iz, jz, descz, work, lwork, iwork, liwork, ifailv, iclustr, gap, info) call pcstein (n, d, e, m, w, iblock, isplit, orfac, z, iz, jz, descz, work, lwork, iwork, liwork, ifailv, iclustr, gap, info) call pzstein (n, d, e, m, w, iblock, isplit, orfac, z, iz, jz, descz, work, lwork, iwork, liwork, ifailv, iclustr, gap, info) ```

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