| // 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 testlapack |
| |
| import ( |
| "math" |
| "testing" |
| |
| "golang.org/x/exp/rand" |
| |
| "gonum.org/v1/gonum/blas" |
| "gonum.org/v1/gonum/blas/blas64" |
| "gonum.org/v1/gonum/floats" |
| ) |
| |
| type Dlarfger interface { |
| Dlarfg(n int, alpha float64, x []float64, incX int) (beta, tau float64) |
| } |
| |
| func DlarfgTest(t *testing.T, impl Dlarfger) { |
| const tol = 1e-14 |
| rnd := rand.New(rand.NewSource(1)) |
| for i, test := range []struct { |
| alpha float64 |
| n int |
| x []float64 |
| }{ |
| { |
| alpha: 4, |
| n: 3, |
| }, |
| { |
| alpha: -2, |
| n: 3, |
| }, |
| { |
| alpha: 0, |
| n: 3, |
| }, |
| { |
| alpha: 1, |
| n: 1, |
| }, |
| { |
| alpha: 1, |
| n: 4, |
| x: []float64{4, 5, 6}, |
| }, |
| { |
| alpha: 1, |
| n: 4, |
| x: []float64{0, 0, 0}, |
| }, |
| { |
| alpha: dlamchS, |
| n: 4, |
| x: []float64{dlamchS, dlamchS, dlamchS}, |
| }, |
| } { |
| n := test.n |
| incX := 1 |
| var x []float64 |
| if test.x == nil { |
| x = make([]float64, n-1) |
| for i := range x { |
| x[i] = rnd.Float64() |
| } |
| } else { |
| if len(test.x) != n-1 { |
| panic("bad test") |
| } |
| x = make([]float64, n-1) |
| copy(x, test.x) |
| } |
| xcopy := make([]float64, n-1) |
| copy(xcopy, x) |
| alpha := test.alpha |
| beta, tau := impl.Dlarfg(n, alpha, x, incX) |
| |
| // Verify the returns and the values in v. Construct h and perform |
| // the explicit multiplication. |
| h := make([]float64, n*n) |
| for i := 0; i < n; i++ { |
| h[i*n+i] = 1 |
| } |
| hmat := blas64.General{ |
| Rows: n, |
| Cols: n, |
| Stride: n, |
| Data: h, |
| } |
| v := make([]float64, n) |
| copy(v[1:], x) |
| v[0] = 1 |
| vVec := blas64.Vector{ |
| Inc: 1, |
| Data: v, |
| } |
| blas64.Ger(-tau, vVec, vVec, hmat) |
| eye := blas64.General{ |
| Rows: n, |
| Cols: n, |
| Stride: n, |
| Data: make([]float64, n*n), |
| } |
| blas64.Gemm(blas.Trans, blas.NoTrans, 1, hmat, hmat, 0, eye) |
| dist := distFromIdentity(n, eye.Data, n) |
| if dist > tol { |
| t.Errorf("Hᵀ * H is not close to I, dist=%v", dist) |
| } |
| |
| xVec := blas64.Vector{ |
| Inc: 1, |
| Data: make([]float64, n), |
| } |
| xVec.Data[0] = test.alpha |
| copy(xVec.Data[1:], xcopy) |
| |
| ans := make([]float64, n) |
| ansVec := blas64.Vector{ |
| Inc: 1, |
| Data: ans, |
| } |
| blas64.Gemv(blas.NoTrans, 1, hmat, xVec, 0, ansVec) |
| if math.Abs(ans[0]-beta) > tol { |
| t.Errorf("Case %v, beta mismatch. Want %v, got %v", i, ans[0], beta) |
| } |
| if floats.Norm(ans[1:n], math.Inf(1)) > tol { |
| t.Errorf("Case %v, nonzero answer %v", i, ans[1:n]) |
| } |
| } |
| } |