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[bytom/vapor.git] / vendor / gonum.org / v1 / gonum / lapack / testlapack / dpbtf2.go

diff --git a/vendor/gonum.org/v1/gonum/lapack/testlapack/dpbtf2.go b/vendor/gonum.org/v1/gonum/lapack/testlapack/dpbtf2.go
new file mode 100644 (file)
index 0000000..2057e28
--- /dev/null
+++ b/vendor/gonum.org/v1/gonum/lapack/testlapack/dpbtf2.go
@@ -0,0 +1,48 @@
+package testlapack
+
+import (
+       "testing"
+
+       "golang.org/x/exp/rand"
+
+       "gonum.org/v1/gonum/blas"
+)
+
+type Dpbtf2er interface {
+       Dpbtf2(ul blas.Uplo, n, kd int, ab []float64, ldab int) (ok bool)
+       Dpotrfer
+}
+
+func Dpbtf2Test(t *testing.T, impl Dpbtf2er) {
+       // Test random symmetric banded matrices against the full version.
+       rnd := rand.New(rand.NewSource(1))
+
+       for _, n := range []int{5, 10, 20} {
+               for _, kb := range []int{0, 1, 3, n - 1} {
+                       for _, ldoff := range []int{0, 4} {
+                               for _, ul := range []blas.Uplo{blas.Upper, blas.Lower} {
+                                       ldab := kb + 1 + ldoff
+                                       sym, band := randSymBand(ul, n, ldab, kb, rnd)
+
+                                       // Compute the Cholesky decomposition of the symmetric matrix.
+                                       ok := impl.Dpotrf(ul, sym.N, sym.Data, sym.Stride)
+                                       if !ok {
+                                               panic("bad test: symmetric cholesky decomp failed")
+                                       }
+
+                                       // Compute the Cholesky decomposition of the banded matrix.
+                                       ok = impl.Dpbtf2(band.Uplo, band.N, band.K, band.Data, band.Stride)
+                                       if !ok {
+                                               t.Errorf("SymBand cholesky decomp failed")
+                                       }
+
+                                       // Compare the result to the Symmetric decomposition.
+                                       sb := symBandToSym(ul, band.Data, n, kb, ldab)
+                                       if !equalApproxSymmetric(sym, sb, 1e-10) {
+                                               t.Errorf("chol mismatch banded and sym. n = %v, kb = %v, ldoff = %v", n, kb, ldoff)
+                                       }
+                               }
+                       }
+               }
+       }
+}