text: #include <stan/math/prim/mat.hpp>
  #include <gtest/gtest.h>
  
  TEST(MathMatrix, row) {
    stan::math::matrix_d m(3, 4);
    m << 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12;
    stan::math::row_vector_d c = m.row(1);
    stan::math::row_vector_d c2 = stan::math::row(m, 2);
    EXPECT_EQ(4, c.size());
    EXPECT_EQ(4, c2.size());
    for (size_t i = 0; i < 4; ++i)
      EXPECT_FLOAT_EQ(c[i], c2[i]);
  }
  
  TEST(MathMatrix, row_exception) {
    stan::math::matrix_d m1(2, 3);
    m1 << 1, 2, 3, 4, 5, 6;
  
    using stan::math::row;
  
    EXPECT_THROW(row(m1, 5), std::out_of_range);
    EXPECT_THROW(row(m1, 0), std::out_of_range);
  }
  