Merge pull request #201 from Bytom/v0.1

[bytom/vapor.git] / vendor / gonum.org / v1 / gonum / lapack / gonum / dlaev2.go

diff --git a/vendor/gonum.org/v1/gonum/lapack/gonum/dlaev2.go b/vendor/gonum.org/v1/gonum/lapack/gonum/dlaev2.go
deleted file mode 100644 (file)
index 74d75b9..0000000
--- a/vendor/gonum.org/v1/gonum/lapack/gonum/dlaev2.go
+++ /dev/null
@@ -1,82 +0,0 @@
-// 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"
-
-// Dlaev2 computes the Eigen decomposition of a symmetric 2×2 matrix.
-// The matrix is given by
-//  [a b]
-//  [b c]
-// Dlaev2 returns rt1 and rt2, the eigenvalues of the matrix where |RT1| > |RT2|,
-// and [cs1, sn1] which is the unit right eigenvalue for RT1.
-//  [ cs1 sn1] [a b] [cs1 -sn1] = [rt1   0]
-//  [-sn1 cs1] [b c] [sn1  cs1]   [  0 rt2]
-//
-// Dlaev2 is an internal routine. It is exported for testing purposes.
-func (impl Implementation) Dlaev2(a, b, c float64) (rt1, rt2, cs1, sn1 float64) {
-       sm := a + c
-       df := a - c
-       adf := math.Abs(df)
-       tb := b + b
-       ab := math.Abs(tb)
-       acmx := c
-       acmn := a
-       if math.Abs(a) > math.Abs(c) {
-               acmx = a
-               acmn = c
-       }
-       var rt float64
-       if adf > ab {
-               rt = adf * math.Sqrt(1+(ab/adf)*(ab/adf))
-       } else if adf < ab {
-               rt = ab * math.Sqrt(1+(adf/ab)*(adf/ab))
-       } else {
-               rt = ab * math.Sqrt(2)
-       }
-       var sgn1 float64
-       if sm < 0 {
-               rt1 = 0.5 * (sm - rt)
-               sgn1 = -1
-               rt2 = (acmx/rt1)*acmn - (b/rt1)*b
-       } else if sm > 0 {
-               rt1 = 0.5 * (sm + rt)
-               sgn1 = 1
-               rt2 = (acmx/rt1)*acmn - (b/rt1)*b
-       } else {
-               rt1 = 0.5 * rt
-               rt2 = -0.5 * rt
-               sgn1 = 1
-       }
-       var cs, sgn2 float64
-       if df >= 0 {
-               cs = df + rt
-               sgn2 = 1
-       } else {
-               cs = df - rt
-               sgn2 = -1
-       }
-       acs := math.Abs(cs)
-       if acs > ab {
-               ct := -tb / cs
-               sn1 = 1 / math.Sqrt(1+ct*ct)
-               cs1 = ct * sn1
-       } else {
-               if ab == 0 {
-                       cs1 = 1
-                       sn1 = 0
-               } else {
-                       tn := -cs / tb
-                       cs1 = 1 / math.Sqrt(1+tn*tn)
-                       sn1 = tn * cs1
-               }
-       }
-       if sgn1 == sgn2 {
-               tn := cs1
-               cs1 = -sn1
-               sn1 = tn
-       }
-       return rt1, rt2, cs1, sn1
-}