vendor/gonum.org/v1/gonum/lapack/testlapack/dpbtf2.go

   1 package testlapack
   2
   3 import (
   4         "testing"
   5
   6         "golang.org/x/exp/rand"
   7
   8         "gonum.org/v1/gonum/blas"
   9 )
  10
  11 type Dpbtf2er interface {
  12         Dpbtf2(ul blas.Uplo, n, kd int, ab []float64, ldab int) (ok bool)
  13         Dpotrfer
  14 }
  15
  16 func Dpbtf2Test(t *testing.T, impl Dpbtf2er) {
  17         // Test random symmetric banded matrices against the full version.
  18         rnd := rand.New(rand.NewSource(1))
  19
  20         for _, n := range []int{5, 10, 20} {
  21                 for _, kb := range []int{0, 1, 3, n - 1} {
  22                         for _, ldoff := range []int{0, 4} {
  23                                 for _, ul := range []blas.Uplo{blas.Upper, blas.Lower} {
  24                                         ldab := kb + 1 + ldoff
  25                                         sym, band := randSymBand(ul, n, ldab, kb, rnd)
  26
  27                                         // Compute the Cholesky decomposition of the symmetric matrix.
  28                                         ok := impl.Dpotrf(ul, sym.N, sym.Data, sym.Stride)
  29                                         if !ok {
  30                                                 panic("bad test: symmetric cholesky decomp failed")
  31                                         }
  32
  33                                         // Compute the Cholesky decomposition of the banded matrix.
  34                                         ok = impl.Dpbtf2(band.Uplo, band.N, band.K, band.Data, band.Stride)
  35                                         if !ok {
  36                                                 t.Errorf("SymBand cholesky decomp failed")
  37                                         }
  38
  39                                         // Compare the result to the Symmetric decomposition.
  40                                         sb := symBandToSym(ul, band.Data, n, kb, ldab)
  41                                         if !equalApproxSymmetric(sym, sb, 1e-10) {
  42                                                 t.Errorf("chol mismatch banded and sym. n = %v, kb = %v, ldoff = %v", n, kb, ldoff)
  43                                         }
  44                                 }
  45                         }
  46                 }
  47         }
  48 }