Function determinant

dependence/eigen-3.4.0/test/determinant.cpp:14–51

#include <Eigen/LU>

template<typename MatrixType> void determinant(const MatrixType& m)
{
  /* this test covers the following files:
     Determinant.h
  */
  Index size = m.rows();

  MatrixType m1(size, size), m2(size, size);
  m1.setRandom();
  m2.setRandom();
  typedef typename MatrixType::Scalar Scalar;
  Scalar x = internal::random<Scalar>();
  VERIFY_IS_APPROX(MatrixType::Identity(size, size).determinant(), Scalar(1));
  VERIFY_IS_APPROX((m1*m2).eval().determinant(), m1.determinant() * m2.determinant());
  if(size==1) return;
  Index i = internal::random<Index>(0, size-1);
  Index j;
  do {
    j = internal::random<Index>(0, size-1);
  } while(j==i);
  m2 = m1;
  m2.row(i).swap(m2.row(j));
  VERIFY_IS_APPROX(m2.determinant(), -m1.determinant());
  m2 = m1;
  m2.col(i).swap(m2.col(j));
  VERIFY_IS_APPROX(m2.determinant(), -m1.determinant());
  VERIFY_IS_APPROX(m2.determinant(), m2.transpose().determinant());
  VERIFY_IS_APPROX(numext::conj(m2.determinant()), m2.adjoint().determinant());
  m2 = m1;
  m2.row(i) += x*m2.row(j);
  VERIFY_IS_APPROX(m2.determinant(), m1.determinant());
  m2 = m1;
  m2.row(i) *= x;
  VERIFY_IS_APPROX(m2.determinant(), m1.determinant() * x);
  
  // check empty matrix
  VERIFY_IS_APPROX(m2.block(0,0,0,0).determinant(), Scalar(1));
}

EIGEN_DECLARE_TEST(determinant)
{