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https://github.com/gonum/gonum.git
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a0a68a3b68
removed unnecessary requirement Implement Dlaswp in both directions Responded to PR comments
96 lines
2.5 KiB
Go
96 lines
2.5 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 (
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"math"
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"github.com/gonum/lapack"
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)
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// Implementation is the native Go implementation of LAPACK routines. It
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// is built on top of calls to the return of blas64.Implementation(), so while
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// this code is in pure Go, the underlying BLAS implementation may not be.
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type Implementation struct{}
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var _ lapack.Float64 = Implementation{}
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// This list is duplicated in lapack/cgo. Keep in sync.
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const (
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absIncNotOne = "lapack: increment not one or negative one"
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badDirect = "lapack: bad direct"
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badIpiv = "lapack: insufficient permutation length"
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badLdA = "lapack: index of a out of range"
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badSide = "lapack: bad side"
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badStore = "lapack: bad store"
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badTau = "lapack: tau has insufficient length"
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badTrans = "lapack: bad trans"
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badUplo = "lapack: illegal triangle"
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badWork = "lapack: insufficient working memory"
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badWorkStride = "lapack: insufficient working array stride"
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negDimension = "lapack: negative matrix dimension"
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nLT0 = "lapack: n < 0"
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shortWork = "lapack: working array shorter than declared"
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)
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// checkMatrix verifies the parameters of a matrix input.
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func checkMatrix(m, n int, a []float64, lda int) {
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if m < 0 {
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panic("lapack: has negative number of rows")
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}
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if m < 0 {
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panic("lapack: has negative number of columns")
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}
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if lda < n {
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panic("lapack: stride less than number of columns")
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}
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if len(a) < (m-1)*lda+n {
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panic("lapack: insufficient matrix slice length")
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}
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}
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func checkVector(n int, v []float64, inc int) {
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if n < 0 {
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panic("lapack: negative matrix length")
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}
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if (inc > 0 && (n-1)*inc >= len(v)) || (inc < 0 && (1-n)*inc >= len(v)) {
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panic("lapack: insufficient vector slice length")
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}
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}
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func min(a, b int) int {
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if a < b {
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return a
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}
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return b
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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// dlamch is a function in fortran, but since go forces IEEE-754 these are all
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// fixed values. Probably a way to get them as constants.
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// TODO(btracey): Is there a better way to find the smallest number such that 1+E > 1
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var dlamchE, dlamchS, dlamchP float64
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func init() {
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onePlusEps := math.Nextafter(1, math.Inf(1))
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eps := (math.Nextafter(1, math.Inf(1)) - 1) * 0.5
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dlamchE = eps
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sfmin := math.SmallestNonzeroFloat64
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small := 1 / math.MaxFloat64
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if small >= sfmin {
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sfmin = small * onePlusEps
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}
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dlamchS = sfmin
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radix := 2.0
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dlamchP = radix * eps
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}
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