fix commands

[bytom/shuttle.git] / vendor / github.com / bytom / vendor / gonum.org / v1 / gonum / lapack / gonum / dlacn2.go

diff --git a/vendor/github.com/bytom/vendor/gonum.org/v1/gonum/lapack/gonum/dlacn2.go b/vendor/github.com/bytom/vendor/gonum.org/v1/gonum/lapack/gonum/dlacn2.go
new file mode 100644 (file)
index 0000000..751d5ca
--- /dev/null
+++ b/vendor/github.com/bytom/vendor/gonum.org/v1/gonum/lapack/gonum/dlacn2.go
@@ -0,0 +1,134 @@
+// 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/blas/blas64"
+)
+
+// Dlacn2 estimates the 1-norm of an n×n matrix A using sequential updates with
+// matrix-vector products provided externally.
+//
+// Dlacn2 is called sequentially and it returns the value of est and kase to be
+// used on the next call.
+// On the initial call, kase must be 0.
+// In between calls, x must be overwritten by
+//  A * X    if kase was returned as 1,
+//  A^T * X  if kase was returned as 2,
+// and all other parameters must not be changed.
+// On the final return, kase is returned as 0, v contains A*W where W is a
+// vector, and est = norm(V)/norm(W) is a lower bound for 1-norm of A.
+//
+// v, x, and isgn must all have length n and n must be at least 1, otherwise
+// Dlacn2 will panic. isave is used for temporary storage.
+//
+// Dlacn2 is an internal routine. It is exported for testing purposes.
+func (impl Implementation) Dlacn2(n int, v, x []float64, isgn []int, est float64, kase int, isave *[3]int) (float64, int) {
+       if n < 1 {
+               panic("lapack: non-positive n")
+       }
+       checkVector(n, x, 1)
+       checkVector(n, v, 1)
+       if len(isgn) < n {
+               panic("lapack: insufficient isgn length")
+       }
+       if isave[0] < 0 || isave[0] > 5 {
+               panic("lapack: bad isave value")
+       }
+       if isave[0] == 0 && kase != 0 {
+               panic("lapack: bad isave value")
+       }
+       itmax := 5
+       bi := blas64.Implementation()
+       if kase == 0 {
+               for i := 0; i < n; i++ {
+                       x[i] = 1 / float64(n)
+               }
+               kase = 1
+               isave[0] = 1
+               return est, kase
+       }
+       switch isave[0] {
+       default:
+               panic("unreachable")
+       case 1:
+               if n == 1 {
+                       v[0] = x[0]
+                       est = math.Abs(v[0])
+                       kase = 0
+                       return est, kase
+               }
+               est = bi.Dasum(n, x, 1)
+               for i := 0; i < n; i++ {
+                       x[i] = math.Copysign(1, x[i])
+                       isgn[i] = int(x[i])
+               }
+               kase = 2
+               isave[0] = 2
+               return est, kase
+       case 2:
+               isave[1] = bi.Idamax(n, x, 1)
+               isave[2] = 2
+               for i := 0; i < n; i++ {
+                       x[i] = 0
+               }
+               x[isave[1]] = 1
+               kase = 1
+               isave[0] = 3
+               return est, kase
+       case 3:
+               bi.Dcopy(n, x, 1, v, 1)
+               estold := est
+               est = bi.Dasum(n, v, 1)
+               sameSigns := true
+               for i := 0; i < n; i++ {
+                       if int(math.Copysign(1, x[i])) != isgn[i] {
+                               sameSigns = false
+                               break
+                       }
+               }
+               if !sameSigns && est > estold {
+                       for i := 0; i < n; i++ {
+                               x[i] = math.Copysign(1, x[i])
+                               isgn[i] = int(x[i])
+                       }
+                       kase = 2
+                       isave[0] = 4
+                       return est, kase
+               }
+       case 4:
+               jlast := isave[1]
+               isave[1] = bi.Idamax(n, x, 1)
+               if x[jlast] != math.Abs(x[isave[1]]) && isave[2] < itmax {
+                       isave[2] += 1
+                       for i := 0; i < n; i++ {
+                               x[i] = 0
+                       }
+                       x[isave[1]] = 1
+                       kase = 1
+                       isave[0] = 3
+                       return est, kase
+               }
+       case 5:
+               tmp := 2 * (bi.Dasum(n, x, 1)) / float64(3*n)
+               if tmp > est {
+                       bi.Dcopy(n, x, 1, v, 1)
+                       est = tmp
+               }
+               kase = 0
+               return est, kase
+       }
+       // Iteration complete. Final stage
+       altsgn := 1.0
+       for i := 0; i < n; i++ {
+               x[i] = altsgn * (1 + float64(i)/float64(n-1))
+               altsgn *= -1
+       }
+       kase = 1
+       isave[0] = 5
+       return est, kase
+}