“…Also, "d" is the first letter in "determinant".) The Chebyshev-Pad6 (1,5), (2,4), and (2, 5) agree with f(x) through less than the expected m + n + 1 terms; the approximant in position (1,4), which also corresponds to a singular Hankel matrix, does have agreement with f(x) through m + n + 1 terms. This triangular nature is typical, with the lower right triangle in a (finite) square block containing "degenerate" approximants.…”