#include #include int main() { using namespace matplot; auto [x, y] = meshgrid(iota(0, 0.2, 2), iota(0, 0.2, 2)); vector_2d u = transform(x, y, [](double x, double y) { return cos(x) * y; }); vector_2d v = transform(x, y, [](double x, double y) { return sin(x) * y; }); quiver(x, y, u, v); show(); return 0; }