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ec100cf00f
Improved function documentation Fixed dlarfb and dlarft and added full tests Added dgelq2 Working Dgels Fix many comments and tests Many PR comment responses Responded to more PR comments Many PR comments
87 lines
2.3 KiB
Go
87 lines
2.3 KiB
Go
// Copyright ©2015 The gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package native
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import "github.com/gonum/blas"
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// Dorm2r multiplies a general matrix c by an orthogonal matrix from a QR factorization
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// determined by Dgeqrf.
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// C = Q * C if side == blas.Left and trans == blas.NoTrans
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// C = Q^T * C if side == blas.Left and trans == blas.Trans
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// C = C * Q if side == blas.Right and trans == blas.NoTrans
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// C = C * Q^T if side == blas.Right and trans == blas.Trans
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// If side == blas.Left, a is a matrix of size m×k, and if side == blas.Right
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// a is of size n×k.
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//
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// Tau contains the householder factors and is of length at least k and this function
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// will panic otherwise.
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//
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// Work is temporary storage of length at least n if side == blas.Left
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// and at least m if side == blas.Right and this function will panic otherwise.
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func (impl Implementation) Dorm2r(side blas.Side, trans blas.Transpose, m, n, k int, a []float64, lda int, tau, c []float64, ldc int, work []float64) {
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if side != blas.Left && side != blas.Right {
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panic(badSide)
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}
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if trans != blas.Trans && trans != blas.NoTrans {
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panic(badTrans)
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}
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left := side == blas.Left
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notran := trans == blas.NoTrans
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if left {
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// Q is m x m
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checkMatrix(m, k, a, lda)
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if len(work) < n {
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panic(badWork)
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}
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} else {
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// Q is n x n
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checkMatrix(n, k, a, lda)
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if len(work) < m {
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panic(badWork)
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}
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}
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checkMatrix(m, n, c, ldc)
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if m == 0 || n == 0 || k == 0 {
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return
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}
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if len(tau) < k {
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panic(badTau)
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}
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if left {
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if notran {
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for i := k - 1; i >= 0; i-- {
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aii := a[i*lda+i]
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a[i*lda+i] = 1
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impl.Dlarf(side, m-i, n, a[i*lda+i:], lda, tau[i], c[i*ldc:], ldc, work)
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a[i*lda+i] = aii
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}
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return
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}
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for i := 0; i < k; i++ {
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aii := a[i*lda+i]
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a[i*lda+i] = 1
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impl.Dlarf(side, m-i, n, a[i*lda+i:], lda, tau[i], c[i*ldc:], ldc, work)
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a[i*lda+i] = aii
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}
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return
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}
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if notran {
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for i := 0; i < k; i++ {
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aii := a[i*lda+i]
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a[i*lda+i] = 1
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impl.Dlarf(side, m, n-i, a[i*lda+i:], lda, tau[i], c[i:], ldc, work)
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a[i*lda+i] = aii
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}
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return
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}
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for i := k - 1; i >= 0; i-- {
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aii := a[i*lda+i]
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a[i*lda+i] = 1
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impl.Dlarf(side, m, n-i, a[i*lda+i:], lda, tau[i], c[i:], ldc, work)
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a[i*lda+i] = aii
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}
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}
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