example1.cpp

// g++ -std=c++17 example1.cpp -O3 -o example1

#include <iostream>

#include "d_rive.h"

using namespace d_rive;

int main()
{
    {
        std::cout << "\nexample: expression definition\n";

        // defines a statement, x<0> are free variables
        auto f = 3_c * (x<0>^2_c) + 2_c * x<0> + 1_c + 3_c;

        // how to print a statement
        std::cout << "expression:\n";
        std::cout << f << "\n";
    }

    {
        std::cout << "\nexample: expression evaluation\n";

        // how to evaluate a statement
        auto f = 3_c * (x<0>^2_c) + 2_c * x<0> + 1_c + 3_c;

        // set<0>(10.) means the variable x<0> is set to 10.
        std::cout << f << "\n";
        std::cout << f(10.) << "\n"; // prints "324"
    }

    {
        std::cout << "\nexample: expression derivation\n";

        // show derivative of the expression
        auto f = 3_c * x<0>*x<0> + 2_c * x<0> + 1_c + 3_c;

        // derive d1
        auto d1 = derive(f, x<0>);
        std::cout << d1 << "\n"; // prints "(2_c + (6_c * x<0>))";

        // derive d2 by deriving from d1
        auto d2a = derive(d1, x<0>);
        std::cout << d2a << "\n"; // prints "6_c";

        // derive d2 by deriving directly from f
        auto d2b = derive<2>(f, x<0>);
        std::cout << d2b << "\n"; // prints "6_c";

        // derive d3 by deriving directly from f
        auto d3 = derive<3>(f, x<0>);
        std::cout << d3 << "\n"; // prints "0_c";

        // derive d4 by deriving directly from f
        auto d4 = derive<4>(f, x<0>);
        std::cout << d4 << "\n"; // prints "0_c";*/
    }
}