www.gusucode.com > symbolic工具箱matlab源码程序 > symbolic/@sym/ztrans.m
function F = ztrans(f,varargin) %ZTRANS Z-transform. % F = ZTRANS(f) is the Z-transform of the sym f with default % independent variable n. The default return is a function of z: % f = f(n) => F = F(z). The Z-transform of f is defined as: % F(z) = symsum(f(n)/z^n, n, 0, inf), % where n is f's symbolic variable as determined by SYMVAR. If % f = f(z), then ZTRANS(f) returns a function of w: F = F(w). % % F = ZTRANS(f,w) makes F a function of the sym w instead of the % default z: ZTRANS(f,w) <=> F(w) = symsum(f(n)/w^n, n, 0, inf). % % F = ZTRANS(f,k,w) takes f to be a function of the sym variable k: % ZTRANS(f,k,w) <=> F(w) = symsum(f(k)/w^k, k, 0, inf). % % Examples: % syms n k w z f(n) % ztrans(2^n) returns z/(z-2) % ztrans(sin(k*n),w) returns (w*sin(k))/(w^2 - 2*cos(k)*w + 1) % ztrans(cos(n*k),k,z) returns (z*(z - cos(n)))/(z^2 - 2*cos(n)*z + 1) % ztrans(cos(n*k),n,w) returns (w*(w - cos(k)))/(w^2 - 2*cos(k)*w + 1) % ztrans(f(n+1)) returns z*ztrans(f(n), n, z) - z*f(0) % % See also SYM/IZTRANS, SYM/LAPLACE, SYM/FOURIER, SUBS. % Copyright 2011 The MathWorks, Inc. F = transform('ztrans', 'n', 'z', 'w', f, varargin{:}); end