SGSSGene / d_rive

c++20 compile time math(derivation/integration) library

d_rive

Compile time math expressions with c++20.

• standard math addition, subtraction, multiplication, division
• sin, cos, pow, ln, sign, abs, max and min
• derivation
• integration

Check example1.cpp and exampleQuat.cpp for more exciting examples.. To try the examples use a modern compiler and compile the .cpp file g++ -std=c++20 example1.cpp.

Examples

(Assume you have using namespace d_rive set)

Lets start with something simple, a constant. Constant have to be written with the _c suffix. that allows us to do everything at compile time. (f() = 5)

    auto f = 5_c;
    std::cout << f << "\n";
    std::cout << f() << "\n";

Lets define a polynomial and print the polynomial (f(x) = x² + 2x + 3)

    auto f = x<0>*x<0> + 2_c * x<0> + 3_c;
    std::cout << f << "\n";

Now lets evaluate it with 5 as x<0> (f(x) = x² + 2x + 3):

    auto f = x<0>*x<0> + 2_c * x<0> + 3_c;
    std::cout << f(5) << "\n";

Easy, right? But what if we need the derivative? (f2 = f')

    auto f2 = derive(f);
    std::cout << f2 << "\n";
    std::cout << f2(5) << "\n";

Derivative of derivates is also possible (f3 = f2')

    auto f3 = derive(f2);
    std::cout << f3 << "\n";

Integrating? (F' = f)

    auto F = integrate(f);
    std::cout << F << "\n";
    std::cout << F(5) << "\n";

Compile time roots? (sqrt(2))

    std::cout << (2_c^0.5_c) << "\n";

Multiple variables: (f(x0, x1, x2) = x0*x1 + x2)

    auto f = x<0>*x<1> + x<2>;
    std::cout << f(1, 2, 3) << "\n";
    std::cout << f << "\n";
    std::cout << derive(f, x<1>) << "\n"; // derives for x<1> instead x<0>

Lets go crazy:

    auto f = 10_c + ((3_c * x<0>) ^ (0.5_c * x<1> * x<2> - x<1>));
    std::cout << derive(f, x<0>) << "\n";
    std::cout << derive(f, x<1>) << "\n";
    std::cout << derive(f, x<2>) << "\n";
    std::cout << integrate(f, x<0>) << "\n";
    std::cout << integrate(f, x<1>) << "\n";
    std::cout << integrate(f, x<2>) << "\n";