mirror of https://github.com/k3s-io/k3s
82 lines
2.1 KiB
Go
82 lines
2.1 KiB
Go
// Copyright ©2018 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 gonum
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import (
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"gonum.org/v1/gonum/blas"
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"gonum.org/v1/gonum/blas/blas64"
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)
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// Dlauum computes the product
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// U * Uᵀ if uplo is blas.Upper
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// Lᵀ * L if uplo is blas.Lower
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// where U or L is stored in the upper or lower triangular part of A.
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// Only the upper or lower triangle of the result is stored, overwriting
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// the corresponding factor in A.
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func (impl Implementation) Dlauum(uplo blas.Uplo, n int, a []float64, lda int) {
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switch {
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case uplo != blas.Upper && uplo != blas.Lower:
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panic(badUplo)
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case n < 0:
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panic(nLT0)
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case lda < max(1, n):
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panic(badLdA)
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}
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// Quick return if possible.
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if n == 0 {
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return
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}
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if len(a) < (n-1)*lda+n {
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panic(shortA)
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}
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// Determine the block size.
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opts := "U"
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if uplo == blas.Lower {
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opts = "L"
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}
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nb := impl.Ilaenv(1, "DLAUUM", opts, n, -1, -1, -1)
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if nb <= 1 || n <= nb {
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// Use unblocked code.
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impl.Dlauu2(uplo, n, a, lda)
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return
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}
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// Use blocked code.
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bi := blas64.Implementation()
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if uplo == blas.Upper {
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// Compute the product U*Uᵀ.
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for i := 0; i < n; i += nb {
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ib := min(nb, n-i)
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bi.Dtrmm(blas.Right, blas.Upper, blas.Trans, blas.NonUnit,
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i, ib, 1, a[i*lda+i:], lda, a[i:], lda)
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impl.Dlauu2(blas.Upper, ib, a[i*lda+i:], lda)
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if n-i-ib > 0 {
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bi.Dgemm(blas.NoTrans, blas.Trans, i, ib, n-i-ib,
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1, a[i+ib:], lda, a[i*lda+i+ib:], lda, 1, a[i:], lda)
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bi.Dsyrk(blas.Upper, blas.NoTrans, ib, n-i-ib,
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1, a[i*lda+i+ib:], lda, 1, a[i*lda+i:], lda)
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}
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}
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} else {
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// Compute the product Lᵀ*L.
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for i := 0; i < n; i += nb {
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ib := min(nb, n-i)
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bi.Dtrmm(blas.Left, blas.Lower, blas.Trans, blas.NonUnit,
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ib, i, 1, a[i*lda+i:], lda, a[i*lda:], lda)
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impl.Dlauu2(blas.Lower, ib, a[i*lda+i:], lda)
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if n-i-ib > 0 {
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bi.Dgemm(blas.Trans, blas.NoTrans, ib, i, n-i-ib,
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1, a[(i+ib)*lda+i:], lda, a[(i+ib)*lda:], lda, 1, a[i*lda:], lda)
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bi.Dsyrk(blas.Lower, blas.Trans, ib, n-i-ib,
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1, a[(i+ib)*lda+i:], lda, 1, a[i*lda+i:], lda)
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}
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}
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}
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}
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