### Refining the Solution and Estimating Its Error

p?gerfs improves the computed solution to a system of linear equations and provides error bounds and backward error estimates for the solution.
``` call psgerfs (trans, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, ipiv, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, iwork, liwork, info) call pdgerfs (trans, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, ipiv, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, iwork, liwork, info) call pcgerfs (trans, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, ipiv, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, rwork, lrwork, info) call pzgerfs (trans, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, ipiv, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, rwork, lrwork, info) ```

p?porfs improves the computed solution to a system of linear equations with symmetric/Hermitian positive-definite distributed matrix and provides error bounds and backward error estimates for the solution.
``` call psporfs (uplo, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, iwork, liwork, info) call pdporfs (uplo, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, iwork, liwork, info) call pcporfs (uplo, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, rwork, lrwork, info) call pzporfs (uplo, n, nrhs, a, ia, ja, desca, af, iaf, jaf, descaf, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, rwork, lrwork, info) ```

p?trrfs provides error bounds and backward error estimates for the solution to a system of linear equations with a distributed triangular coefficient matrix.
``` call pstrrfs (uplo, trans, diag, n, nrhs, a, ia, ja, desca, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, iwork, liwork, info) call pdtrrfs (uplo, trans, diag, n, nrhs, a, ia, ja, desca, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, iwork, liwork, info) call pctrrfs (uplo, trans, diag, n, nrhs, a, ia, ja, desca, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, rwork, lrwork, info) call pztrrfs (uplo, trans, diag, n, nrhs, a, ia, ja, desca, b, ib, jb, descb, x, ix, jx, descx, ferr, berr, work, lwork, rwork, lrwork, info) ```

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