gusucode.com > elmat工具箱matlab源码程序 > elmat/private/binomial.m
function A = binomial(n,classname) %BINOMIAL Binomial matrix (multiple of involutory matrix). % A = GALLERY('BINOMIAL',N) is an N-by-N matrix with integer entries % such that A^2 = 2^(N-1)*EYE(N). % Thus B = A*2^((1-N)/2) is involutory, that is, B^2 = EYE(N). % Reference: % G. Boyd, C. A. Micchelli, G. Strang and D.-X. Zhou, % Binomial matrices, Adv. in Comput. Math., 14 (2001), pp. 379-391. % % Nicholas J. Higham % Copyright 1984-2005 The MathWorks, Inc. L = abs( pascal(n,1,classname) ); U = L(n:-1:1,n:-1:1); D = diag( (-2).^(0:n-1) ); A = L*D*U;