Question

我正在尝试使用Eigen库。但是当我尝试使用XCode在OSX Mavericks下编译时，我收到以下错误消息：

Undefined symbols for architecture x86_64:
  "buildProblem(std::__1::vector<Eigen::Triplet<double, int>,  std::__1::allocator<Eigen::Triplet<double, int> > >&, Eigen::Matrix<double, -1, 1, 0, -1, 1>&, int)", referenced from:
  _main in main.o
  "saveAsBitmap(Eigen::Matrix<double, -1, 1, 0, -1, 1> const&, int, char const*)", referenced from:
  _main in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

我的代码或设置有什么问题？在这里你可以看到我的代码：

#include <iostream>
#include </usr/local/include/Eigen/Eigen/Sparse>
#include <vector>


typedef Eigen::SparseMatrix<double> SpMat; // declares a column-major sparse matrix type of double
typedef Eigen::Triplet<double> T;
void buildProblem(std::vector<T>& coefficients, Eigen::VectorXd& b, int n);
void saveAsBitmap(const Eigen::VectorXd& x, int n, const char* filename);



int main(int argc, char** argv)
{
    int n = 300;  // size of the image
   int m = n*n;  // number of unknows (=number of pixels)
    // Assembly:
    std::vector<T> coefficients;            // list of non-zeros coefficients
    Eigen::VectorXd b(m);                   // the right hand side-vector resulting from the constraints
    buildProblem(coefficients, b, n);
    SpMat A(m,m);
    A.setFromTriplets(coefficients.begin(), coefficients.end());
    // Solving:
    Eigen::SimplicialCholesky<SpMat> chol(A);  // performs a Cholesky factorization of A
    Eigen::VectorXd x = chol.solve(b);         // use the factorization to solve for the given right hand side
    // Export the result to a file:
    saveAsBitmap(x, n, argv[1]);
    return 0;
}

Answer 1

编译该示例代码所需的缺失函数saveAsBitmap()，buildProblem()和其他定义发布在this link。

CMakeLists.txt文件位于同一存储库中的one directory above。我必须在该文件中添加一行cmake_minimum_required(VERSION 3.2) 删除行add_dependencies(all_examples Tutorial_sparse_example)以编译代码，现在可以正常工作。

Answer 2

您需要包含具有saveAsBitmap和buildProblem函数定义的头文件。

C ++ - 使用eigen构建时未找到的符号

2 个答案: