29 lines
968 B
C++
29 lines
968 B
C++
// NOTE: 标量函数的梯度向量
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// C++ includes
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#include <iostream>
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// autodiff include
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#include <autodiff/forward/real.hpp>
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#include <autodiff/forward/real/eigen.hpp>
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using namespace autodiff;
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// The scalar function for which the gradient is needed
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real f(const ArrayXreal& x)
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{
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return (x * x.exp()).sum(); // sum([xi * exp(xi) for i = 1:5])
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}
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int main()
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{
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using Eigen::VectorXd;
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ArrayXreal x(5); // the input array x with 5 variables
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x << 1, 2, 3, 4, 5; // x = [1, 2, 3, 4, 5]
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real u; // the output scalar u = f(x) evaluated together with gradient below
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VectorXd g = gradient(f, wrt(x), at(x), u); // evaluate the function value u and its gradient vector g = du/dx
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std::cout << "u = " << u << std::endl; // print the evaluated output u
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std::cout << "g = \n" << g << std::endl; // print the evaluated gradient vector g = du/dx
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} |