public void DifferentiateMexicanHatTest()
{
var differentiator = new Differentiator();
var dx = differentiator.Differentiate("sin(sqrt(x^2+y^2))", "x", true);
var res = differentiator.Differentiate(dx, "y", true);
dx = differentiator.Differentiate("sin(sqrt(x^2+y^2))", "y", true);
res = differentiator.Differentiate(dx, "x", true);
}
void AssertSyntacticDerivativeEqualToNumericDerivative(Expression <Func <double, double> > func)
{
var f = func.Compile();
double eps = 1e-7;
var dfExpression = Differentiator.Differentiate(func);
var df = dfExpression.Compile();
for (double x = 0.5; x < 10; x += 0.5)
{
Assert.AreEqual((f(x + eps) - f(x - eps)) / (2 * eps), df(x), 1e-4);
}
}
public void DifferentiateXYTest()
{
var differentiator = new Differentiator();
var d = differentiator.Differentiate("x^2+y^2", "x", true);
var res = differentiator.Differentiate(d, "y", true);
d = differentiator.Differentiate("x^2+y^2", "y", true);
res = differentiator.Differentiate(d, "x", true);
d = differentiator.Differentiate("x^y", "x", true);
// toto nezvladne t.j y*x^(y-1) podla y
res = differentiator.Differentiate(d, "y", true);
d = differentiator.Differentiate("x^y", "y", true);
res = differentiator.Differentiate(d, "x", true);
}