cpp-mathmatic-matrix/matrix_helper_test.cpp

//
//  matrix_helper_test.cpp
//  matrix
//
//  Created by Sam Jaffe on 6/3/18.
//

#include <gmock/gmock.h>

#include "matrix_helpers.hpp"

template <std::size_t N> using vec = math::vector::vector<double, N>;

TEST(MatrixHelper, IdentityFunctionProducesOnes) {
  auto iden = math::matrix::identity<double, 4>();
  VECTOR_FOR_EACH_RANGE(i, 4) {
    EXPECT_THAT(iden.at(i, i), 1.0);
  }
  MATRIX_FOR_EACH_RANGE(i, 4, j, 4) {
    EXPECT_TRUE(i == j || iden.at(i, j) == 0);
  }
}

TEST(MatrixHelper, DiagonalWillFillWithAllZeros) {
  vec<4> const vector({1.5, 0.5, -1.0, 2.2});
  auto diag = math::matrix::diagonal(vector);
  VECTOR_FOR_EACH_RANGE(i, 4) {
    EXPECT_THAT(diag.at(i, i), vector.at(i));
  }
  MATRIX_FOR_EACH_RANGE(i, 4, j, 4) {
    EXPECT_TRUE(i == j || diag.at(i, j) == 0);
  }
}

TEST(MatrixHelper, ScalarMatrixPiecewiseStretchesVector) {
  vec<3> const vector({1.5, 0.5, -1.0});
  vec<3> const x({2.0, 3.8, 11.0});
  auto const A = math::matrix::scalar(vector);
  EXPECT_THAT(A*x, vec<3>({3.0, 1.9, -11.0}));
}