diff --git a/go/types/hilbert_test.go b/go/types/hilbert_test.go new file mode 100644 index 00000000..298d1ca7 --- /dev/null +++ b/go/types/hilbert_test.go @@ -0,0 +1,232 @@ +// Copyright 2013 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. + +package types_test + +import ( + "bytes" + "flag" + "fmt" + "go/ast" + "go/parser" + "go/token" + "io/ioutil" + "testing" + + . "code.google.com/p/go.tools/go/types" +) + +var ( + H = flag.Int("H", 5, "Hilbert matrix size") + out = flag.String("out", "", "write generated program to out") +) + +func TestHilbert(t *testing.T) { + // generate source + src := program(*H, *out) + if *out != "" { + ioutil.WriteFile(*out, src, 0666) + return + } + + // parse source + fset := token.NewFileSet() + f, err := parser.ParseFile(fset, "hilbert.go", src, 0) + if err != nil { + t.Fatal(err) + } + + // type-check file + DefPredeclaredTestFuncs() // define assert built-in + _, err = Check(f.Name.Name, fset, []*ast.File{f}) + if err != nil { + t.Fatal(err) + } +} + +func program(n int, out string) []byte { + var g gen + + g.p(`// WARNING: GENERATED FILE - DO NOT MODIFY MANUALLY! +// (To generate, in go/types directory: go test -run=Hilbert -H=%d -out=%q) + +// This program tests arbitrary precision constant arithmetic +// by generating the constant elements of a Hilbert matrix H, +// its inverse I, and the product P = H*I. The product should +// be the identity matrix. +package main + +func main() { + if !ok { + printProduct() + return + } + println("PASS") +} + +`, n, out) + g.hilbert(n) + g.inverse(n) + g.product(n) + g.verify(n) + g.printProduct(n) + g.binomials(2*n - 1) + g.factorials(2*n - 1) + + return g.Bytes() +} + +type gen struct { + bytes.Buffer +} + +func (g *gen) p(format string, args ...interface{}) { + fmt.Fprintf(&g.Buffer, format, args...) +} + +func (g *gen) hilbert(n int) { + g.p(`// Hilbert matrix, n = %d +const ( +`, n) + for i := 0; i < n; i++ { + g.p("\t") + for j := 0; j < n; j++ { + if j > 0 { + g.p(", ") + } + g.p("h%d_%d", i, j) + } + if i == 0 { + g.p(" = ") + for j := 0; j < n; j++ { + if j > 0 { + g.p(", ") + } + g.p("1.0/(iota + %d)", j+1) + } + } + g.p("\n") + } + g.p(")\n\n") +} + +func (g *gen) inverse(n int) { + g.p(`// Inverse Hilbert matrix +const ( +`) + for i := 0; i < n; i++ { + for j := 0; j < n; j++ { + s := "+" + if (i+j)&1 != 0 { + s = "-" + } + g.p("\ti%d_%d = %s%d * b%d_%d * b%d_%d * b%d_%d * b%d_%d\n", + i, j, s, i+j+1, n+i, n-j-1, n+j, n-i-1, i+j, i, i+j, i) + } + g.p("\n") + } + g.p(")\n\n") +} + +func (g *gen) product(n int) { + g.p(`// Product matrix +const ( +`) + for i := 0; i < n; i++ { + for j := 0; j < n; j++ { + g.p("\tp%d_%d = ", i, j) + for k := 0; k < n; k++ { + if k > 0 { + g.p(" + ") + } + g.p("h%d_%d*i%d_%d", i, k, k, j) + } + g.p("\n") + } + g.p("\n") + } + g.p(")\n\n") +} + +func (g *gen) verify(n int) { + g.p(`// Verify that product is the identity matrix +const ok = +`) + for i := 0; i < n; i++ { + for j := 0; j < n; j++ { + if j == 0 { + g.p("\t") + } else { + g.p(" && ") + } + v := 0 + if i == j { + v = 1 + } + g.p("p%d_%d == %d", i, j, v) + } + g.p(" &&\n") + } + g.p("\ttrue\n\n") + + // verify ok at type-check time + if *out == "" { + g.p("const _ = assert(ok)\n\n") + } +} + +func (g *gen) printProduct(n int) { + g.p("func printProduct() {\n") + for i := 0; i < n; i++ { + g.p("\tprintln(") + for j := 0; j < n; j++ { + if j > 0 { + g.p(", ") + } + g.p("p%d_%d", i, j) + } + g.p(")\n") + } + g.p("}\n\n") +} + +func (g *gen) mulRange(a, b int) { + if a > b { + g.p("1") + return + } + for i := a; i <= b; i++ { + if i > a { + g.p("*") + } + g.p("%d", i) + } +} + +func (g *gen) binomials(n int) { + g.p(`// Binomials +const ( +`) + for j := 0; j <= n; j++ { + if j > 0 { + g.p("\n") + } + for k := 0; k <= j; k++ { + g.p("\tb%d_%d = f%d / (f%d*f%d)\n", j, k, j, k, j-k) + } + } + g.p(")\n\n") +} + +func (g *gen) factorials(n int) { + g.p(`// Factorials +const ( + f0 = 1 + f1 = 1 +`) + for i := 2; i <= n; i++ { + g.p("\tf%d = f%d * %d\n", i, i-1, i) + } + g.p(")\n\n") +}