| // Copyright ©2016 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" |
| "math/rand" |
| "testing" |
| |
| "gonum.org/v1/gonum/blas" |
| "gonum.org/v1/gonum/blas/blas64" |
| ) |
| |
| type Dlacn2er interface { |
| Dlacn2(n int, v, x []float64, isgn []int, est float64, kase int, isave *[3]int) (float64, int) |
| } |
| |
| func Dlacn2Test(t *testing.T, impl Dlacn2er) { |
| rnd := rand.New(rand.NewSource(1)) |
| for _, n := range []int{1, 2, 3, 4, 5, 7, 10, 15, 20, 100} { |
| for cas := 0; cas < 10; cas++ { |
| a := randomGeneral(n, n, n, rnd) |
| |
| // Compute the 1-norm of A explicitly. |
| var norm1 float64 |
| for j := 0; j < n; j++ { |
| var sum float64 |
| for i := 0; i < n; i++ { |
| sum += math.Abs(a.Data[i*a.Stride+j]) |
| } |
| if sum > norm1 { |
| norm1 = sum |
| } |
| } |
| |
| // Compute the estimate of 1-norm using Dlanc2. |
| x := make([]float64, n) |
| work := make([]float64, n) |
| v := make([]float64, n) |
| isgn := make([]int, n) |
| var ( |
| kase int |
| isave [3]int |
| got float64 |
| ) |
| loop: |
| for { |
| got, kase = impl.Dlacn2(n, v, x, isgn, got, kase, &isave) |
| switch kase { |
| default: |
| panic("Dlacn2 returned invalid value of kase") |
| case 0: |
| break loop |
| case 1: |
| blas64.Gemv(blas.NoTrans, 1, a, blas64.Vector{1, x}, 0, blas64.Vector{1, work}) |
| copy(x, work) |
| case 2: |
| blas64.Gemv(blas.Trans, 1, a, blas64.Vector{1, x}, 0, blas64.Vector{1, work}) |
| copy(x, work) |
| } |
| } |
| |
| // Check that got is either accurate enough or a |
| // lower estimate of the 1-norm of A. |
| if math.Abs(got-norm1) > 1e-8 && got > norm1 { |
| t.Errorf("Case n=%v: not lower estimate. 1-norm %v, estimate %v", n, norm1, got) |
| } |
| } |
| } |
| } |