Introduction to Matrix Types in Linear Algebra for Machine Learning - Machine Learning Mastery

To be symmetric, the axis of symmetry is always the main diagonal of the matrix, from the top left to the bottom right. Below is an example of a 5 5 symmetric matrix. A symmetric matrix is always square and equal to its own transpose. A triangular matrix is a type of square matrix that has all values in the upper-right or lower-left of the matrix with the remaining elements filled with zero values. A triangular matrix with values only above the main diagonal is called an upper triangular matrix.