public void ReplaceFunctionDerivative()
{
var x = new Symbol("x");
var f = new SymbolFunction("f", x);
Assert.IsTrue(_.Same(1 + 2 * x, (1 + f.D()._(x)).Replace(
new Rule(f._(~x), _.Pow(x, 2)))));
Assert.IsTrue(_.Same(4 * x, (f.D()._(2 * x)).Replace(
new Rule(f._(~x), _.Pow(x, 2)))));
}
public override Expression On(SymbolFunction e)
{
return(e.Arguments
.Select((arg, i) => e.D(i) * _.D(arg, x))
.Aggregate((a, b) => a + b));
}
