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Diffstat (limited to 'src/pkg/math/big/hilbert_test.go')
-rw-r--r-- | src/pkg/math/big/hilbert_test.go | 160 |
1 files changed, 0 insertions, 160 deletions
diff --git a/src/pkg/math/big/hilbert_test.go b/src/pkg/math/big/hilbert_test.go deleted file mode 100644 index 1a84341b3..000000000 --- a/src/pkg/math/big/hilbert_test.go +++ /dev/null @@ -1,160 +0,0 @@ -// Copyright 2009 The Go Authors. All rights reserved. -// Use of this source code is governed by a BSD-style -// license that can be found in the LICENSE file. - -// A little test program and benchmark for rational arithmetics. -// Computes a Hilbert matrix, its inverse, multiplies them -// and verifies that the product is the identity matrix. - -package big - -import ( - "fmt" - "testing" -) - -type matrix struct { - n, m int - a []*Rat -} - -func (a *matrix) at(i, j int) *Rat { - if !(0 <= i && i < a.n && 0 <= j && j < a.m) { - panic("index out of range") - } - return a.a[i*a.m+j] -} - -func (a *matrix) set(i, j int, x *Rat) { - if !(0 <= i && i < a.n && 0 <= j && j < a.m) { - panic("index out of range") - } - a.a[i*a.m+j] = x -} - -func newMatrix(n, m int) *matrix { - if !(0 <= n && 0 <= m) { - panic("illegal matrix") - } - a := new(matrix) - a.n = n - a.m = m - a.a = make([]*Rat, n*m) - return a -} - -func newUnit(n int) *matrix { - a := newMatrix(n, n) - for i := 0; i < n; i++ { - for j := 0; j < n; j++ { - x := NewRat(0, 1) - if i == j { - x.SetInt64(1) - } - a.set(i, j, x) - } - } - return a -} - -func newHilbert(n int) *matrix { - a := newMatrix(n, n) - for i := 0; i < n; i++ { - for j := 0; j < n; j++ { - a.set(i, j, NewRat(1, int64(i+j+1))) - } - } - return a -} - -func newInverseHilbert(n int) *matrix { - a := newMatrix(n, n) - for i := 0; i < n; i++ { - for j := 0; j < n; j++ { - x1 := new(Rat).SetInt64(int64(i + j + 1)) - x2 := new(Rat).SetInt(new(Int).Binomial(int64(n+i), int64(n-j-1))) - x3 := new(Rat).SetInt(new(Int).Binomial(int64(n+j), int64(n-i-1))) - x4 := new(Rat).SetInt(new(Int).Binomial(int64(i+j), int64(i))) - - x1.Mul(x1, x2) - x1.Mul(x1, x3) - x1.Mul(x1, x4) - x1.Mul(x1, x4) - - if (i+j)&1 != 0 { - x1.Neg(x1) - } - - a.set(i, j, x1) - } - } - return a -} - -func (a *matrix) mul(b *matrix) *matrix { - if a.m != b.n { - panic("illegal matrix multiply") - } - c := newMatrix(a.n, b.m) - for i := 0; i < c.n; i++ { - for j := 0; j < c.m; j++ { - x := NewRat(0, 1) - for k := 0; k < a.m; k++ { - x.Add(x, new(Rat).Mul(a.at(i, k), b.at(k, j))) - } - c.set(i, j, x) - } - } - return c -} - -func (a *matrix) eql(b *matrix) bool { - if a.n != b.n || a.m != b.m { - return false - } - for i := 0; i < a.n; i++ { - for j := 0; j < a.m; j++ { - if a.at(i, j).Cmp(b.at(i, j)) != 0 { - return false - } - } - } - return true -} - -func (a *matrix) String() string { - s := "" - for i := 0; i < a.n; i++ { - for j := 0; j < a.m; j++ { - s += fmt.Sprintf("\t%s", a.at(i, j)) - } - s += "\n" - } - return s -} - -func doHilbert(t *testing.T, n int) { - a := newHilbert(n) - b := newInverseHilbert(n) - I := newUnit(n) - ab := a.mul(b) - if !ab.eql(I) { - if t == nil { - panic("Hilbert failed") - } - t.Errorf("a = %s\n", a) - t.Errorf("b = %s\n", b) - t.Errorf("a*b = %s\n", ab) - t.Errorf("I = %s\n", I) - } -} - -func TestHilbert(t *testing.T) { - doHilbert(t, 10) -} - -func BenchmarkHilbert(b *testing.B) { - for i := 0; i < b.N; i++ { - doHilbert(nil, 10) - } -} |