This is a C++14 library offering a way to compile-time derive a mathematical function, so run-time only the derivative is executed. This technique is called Automatic differentiation, hence the name of the lib.
Example:
#include "auto_derive/all.hpp"
int main() {
AUTO_DERIVE_VARIABLE(double, x);
AUTO_DERIVE_VARIABLE(double, y);
constexpr auto f = pow(x+y, 3) - 2*x*y;
constexpr auto dfdy = derive(f, y);
double dfdy_evaluated = dfdy(x=2, y=4.2);
std::cout << "derive(" << f << ", " << y << ") = " << dfdy << std::endl;
std::cout << dfdy << " if x=2 and y=4.2 is " << dfdy_evaluated << std::endl;
}It will result the following output:
derive(pow(x+y,3)-2*x*y, y) = 3*pow(x+y,2)-2*x
3*pow(x+y,2)-2*x if x=2 and y=4.2 is 111.32For more details see how_to_use.cpp.