Ticket #2704: Expression Generator Code Sample.cs

public static Expression Polynomial(IRandom uniformRandom, Expression[] variables, bool useLog, bool useExp) {
    var sumTemplate = new RandomArityTemplate(Sum, new UniformDistributedRandom(uniformRandom, 1, variables.Length)) { Label = "+" };
    sumTemplate.AddArguments(variables);

    var productTemplate = new RandomArityTemplate(Product, new UniformDistributedRandom(uniformRandom, 1, variables.Length)) { Label = "*" };
    productTemplate.AddArguments(variables);

    const int count = 10; // how many instances of each template should be produced?
    int i = 1;

    var logTemplate = new FixedArityTemplate(Log, 1) { Label = "log" };
    logTemplate.AddArguments(variables);
    logTemplate.AddArguments(Enumerable.Range(1, count).Select(x => sumTemplate.Instantiate(string.Format("sum{0}", i++), uniformRandom)));

    var expTemplate = new FixedArityTemplate(Exp, 1) { Label = "exp" };
    expTemplate.AddArguments(variables);
    expTemplate.AddArguments(Enumerable.Range(1, count).Select(x => productTemplate.Instantiate(string.Format("prod{0}", i++), uniformRandom)));

    var inverseTemplate = new FixedArityTemplate(Division, 1) { Label = "/" };
    inverseTemplate.AddArguments(variables);
    inverseTemplate.AddArguments(Enumerable.Range(1, count).Select(x => sumTemplate.Instantiate(string.Format("sum{0}", i++), uniformRandom)));
    inverseTemplate.AddArguments(Enumerable.Range(1, count).Select(x => productTemplate.Instantiate(string.Format("prod{0}", i++), uniformRandom)));
    inverseTemplate.AddArguments(Enumerable.Range(1, count).Select(x => logTemplate.Instantiate(string.Format("log{0}", i++), uniformRandom)));
    inverseTemplate.AddArguments(Enumerable.Range(1, count).Select(x => expTemplate.Instantiate(string.Format("exp{0}", i++), uniformRandom)));

    var template = new RandomArityTemplate(Sum, new UniformDistributedRandom(uniformRandom, 2, count)) { Label = "+" };
    template.AddArguments(variables);
    template.AddArguments(Enumerable.Range(1, count).Select(x => logTemplate.Instantiate(string.Format("log{0}", i++), uniformRandom)));
    template.AddArguments(Enumerable.Range(1, count).Select(x => expTemplate.Instantiate(string.Format("exp{0}", i++), uniformRandom)));
    template.AddArguments(Enumerable.Range(1, count).Select(x => inverseTemplate.Instantiate(string.Format("inv{0}", i++), uniformRandom)));

    return template.Instantiate("polynomial", uniformRandom);
}