728e29aa7e
2. add a dummy file tools.go to force "go mod vendor" to see code-generator as dependencies 3. add a script to update CRD 4. add a README to document CRD updating steps run go mod tidy update README
90 lines
2.3 KiB
Go
90 lines
2.3 KiB
Go
// 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 (
|
||
"math"
|
||
|
||
"gonum.org/v1/gonum/lapack"
|
||
)
|
||
|
||
// Dlange computes the matrix norm of the general m×n matrix a. The input norm
|
||
// specifies the norm computed.
|
||
// lapack.MaxAbs: the maximum absolute value of an element.
|
||
// lapack.MaxColumnSum: the maximum column sum of the absolute values of the entries.
|
||
// lapack.MaxRowSum: the maximum row sum of the absolute values of the entries.
|
||
// lapack.Frobenius: the square root of the sum of the squares of the entries.
|
||
// If norm == lapack.MaxColumnSum, work must be of length n, and this function will panic otherwise.
|
||
// There are no restrictions on work for the other matrix norms.
|
||
func (impl Implementation) Dlange(norm lapack.MatrixNorm, m, n int, a []float64, lda int, work []float64) float64 {
|
||
// TODO(btracey): These should probably be refactored to use BLAS calls.
|
||
switch {
|
||
case norm != lapack.MaxRowSum && norm != lapack.MaxColumnSum && norm != lapack.Frobenius && norm != lapack.MaxAbs:
|
||
panic(badNorm)
|
||
case lda < max(1, n):
|
||
panic(badLdA)
|
||
}
|
||
|
||
// Quick return if possible.
|
||
if m == 0 || n == 0 {
|
||
return 0
|
||
}
|
||
|
||
switch {
|
||
case len(a) < (m-1)*lda+n:
|
||
panic(badLdA)
|
||
case norm == lapack.MaxColumnSum && len(work) < n:
|
||
panic(shortWork)
|
||
}
|
||
|
||
if norm == lapack.MaxAbs {
|
||
var value float64
|
||
for i := 0; i < m; i++ {
|
||
for j := 0; j < n; j++ {
|
||
value = math.Max(value, math.Abs(a[i*lda+j]))
|
||
}
|
||
}
|
||
return value
|
||
}
|
||
if norm == lapack.MaxColumnSum {
|
||
if len(work) < n {
|
||
panic(shortWork)
|
||
}
|
||
for i := 0; i < n; i++ {
|
||
work[i] = 0
|
||
}
|
||
for i := 0; i < m; i++ {
|
||
for j := 0; j < n; j++ {
|
||
work[j] += math.Abs(a[i*lda+j])
|
||
}
|
||
}
|
||
var value float64
|
||
for i := 0; i < n; i++ {
|
||
value = math.Max(value, work[i])
|
||
}
|
||
return value
|
||
}
|
||
if norm == lapack.MaxRowSum {
|
||
var value float64
|
||
for i := 0; i < m; i++ {
|
||
var sum float64
|
||
for j := 0; j < n; j++ {
|
||
sum += math.Abs(a[i*lda+j])
|
||
}
|
||
value = math.Max(value, sum)
|
||
}
|
||
return value
|
||
}
|
||
// norm == lapack.Frobenius
|
||
var value float64
|
||
scale := 0.0
|
||
sum := 1.0
|
||
for i := 0; i < m; i++ {
|
||
scale, sum = impl.Dlassq(n, a[i*lda:], 1, scale, sum)
|
||
}
|
||
value = scale * math.Sqrt(sum)
|
||
return value
|
||
}
|