| // Copyright ©2015 The gonum Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| package gonum |
| |
| import "gonum.org/v1/gonum/blas" |
| |
| // Dormr2 multiplies a general matrix C by an orthogonal matrix from a RQ factorization |
| // determined by Dgerqf. |
| // C = Q * C if side == blas.Left and trans == blas.NoTrans |
| // C = Q^T * C if side == blas.Left and trans == blas.Trans |
| // C = C * Q if side == blas.Right and trans == blas.NoTrans |
| // C = C * Q^T if side == blas.Right and trans == blas.Trans |
| // If side == blas.Left, a is a matrix of size k×m, and if side == blas.Right |
| // a is of size k×n. |
| // |
| // tau contains the Householder factors and is of length at least k and this function |
| // will panic otherwise. |
| // |
| // work is temporary storage of length at least n if side == blas.Left |
| // and at least m if side == blas.Right and this function will panic otherwise. |
| // |
| // Dormr2 is an internal routine. It is exported for testing purposes. |
| func (impl Implementation) Dormr2(side blas.Side, trans blas.Transpose, m, n, k int, a []float64, lda int, tau, c []float64, ldc int, work []float64) { |
| if side != blas.Left && side != blas.Right { |
| panic(badSide) |
| } |
| if trans != blas.Trans && trans != blas.NoTrans { |
| panic(badTrans) |
| } |
| |
| left := side == blas.Left |
| notran := trans == blas.NoTrans |
| if left { |
| if k > m { |
| panic(kGTM) |
| } |
| checkMatrix(k, m, a, lda) |
| if len(work) < n { |
| panic(badWork) |
| } |
| } else { |
| if k > n { |
| panic(kGTN) |
| } |
| checkMatrix(k, n, a, lda) |
| if len(work) < m { |
| panic(badWork) |
| } |
| } |
| if len(tau) < k { |
| panic(badTau) |
| } |
| checkMatrix(m, n, c, ldc) |
| |
| if m == 0 || n == 0 || k == 0 { |
| return |
| } |
| if left { |
| if notran { |
| for i := k - 1; i >= 0; i-- { |
| aii := a[i*lda+(m-k+i)] |
| a[i*lda+(m-k+i)] = 1 |
| impl.Dlarf(side, m-k+i+1, n, a[i*lda:], 1, tau[i], c, ldc, work) |
| a[i*lda+(m-k+i)] = aii |
| } |
| return |
| } |
| for i := 0; i < k; i++ { |
| aii := a[i*lda+(m-k+i)] |
| a[i*lda+(m-k+i)] = 1 |
| impl.Dlarf(side, m-k+i+1, n, a[i*lda:], 1, tau[i], c, ldc, work) |
| a[i*lda+(m-k+i)] = aii |
| } |
| return |
| } |
| if notran { |
| for i := 0; i < k; i++ { |
| aii := a[i*lda+(n-k+i)] |
| a[i*lda+(n-k+i)] = 1 |
| impl.Dlarf(side, m, n-k+i+1, a[i*lda:], 1, tau[i], c, ldc, work) |
| a[i*lda+(n-k+i)] = aii |
| } |
| return |
| } |
| for i := k - 1; i >= 0; i-- { |
| aii := a[i*lda+(n-k+i)] |
| a[i*lda+(n-k+i)] = 1 |
| impl.Dlarf(side, m, n-k+i+1, a[i*lda:], 1, tau[i], c, ldc, work) |
| a[i*lda+(n-k+i)] = aii |
| } |
| } |