president_matrix, an Octave code which defines a sort of graph "adjacency" matrix for US presidents. Presidents I and J are "adjacent" if there was any year in which they were both alive, that is, if their lifespans overlap.
As a mathematical note, this adjacency relationship is reflexive (A(i,i)=1) and symmetric (A(i,j)=A(j,i)), but not transitive (A(i,j)=1 and A(j,k)=1 does not imply A(i,k)=1).
The information on this web page is distributed under the MIT license.
president_matrix is available in a MATLAB version and an Octave version and a Python version.
chebyshev_matrix, an Octave code which defines the Chebyshev differentiation matrix, by Lloyd Trefethen.
jordan_matrix, an Octave code which returns a random matrix in Jordan canonical form.
levenshtein_matrix, an Octave code which returns the Levenshtein distance matrix defined by two strings.
magic_matrix, an Octave code which computes a magic matrix, for any odd order n, such that all rows and columns have the same sum.
monopoly_matrix, an Octave code which computes the adjacency and transition matrices for the game of Monopoly.
neighbor_states, an Octave code which records information about pairs of US states which are neighbors.
plasma_matrix, an Octave code which sets up a matrix associated with a problem in plasma physics.
presidents, a dataset directory which contains data related to US presidents.
risk_matrix, an Octave code which computes the transition and adjacency matrix for the game of RISK.
snakes_matrix, an Octave code which computes the transition matrix for Snakes and Ladders.
tennis_matrix, an Octave code which computes the transition matrix for a game of tennis, which has 17 distinct states.
test_matrix, an Octave code which defines test matrices for which the condition number, determinant, eigenvalues, eigenvectors, inverse, null vectors, P*L*U factorization or linear system solution are known. Examples include the Fibonacci, Hilbert, Redheffer, Vandermonde, Wathen and Wilkinson matrices.
usa_matrix, an Octave code which defines the adjacency matrix for US states, using a variety of matrix formats.
wathen_matrix, an Octave code which compares storage schemes (full, banded, sparse triplet, sparse) and solution strategies (A\x, linpack, conjugate gradient (CG)) for linear systems involving the Wathen matrix, which can arise when solving a problem using the finite element method (FEM).
web_matrix, an Octave code which stores sample matrices describing a web page network. These matrices are typically very sparse, and the examples here are stored using the sparse triplet (ST) format. They can be used to demonstrate pagerank and other graph algorithms.
wishart_matrix, an Octave code which produces sample matrices from the Wishart or Bartlett distributions, useful for sampling random covariance matrices.