摘要: 习题IV.2 定义f为仿射保持(Affine Preserved)的,如果对任意向量x1和x2有f((1 - a) * x1 + a * x2) = (1 - a) * f(x1) + a * f(x2),证明:f仿射保持的充要条件是f是仿射变换。 证:充分性易证,只证必要性。由仿射保持性,f(a * x)= f(a * x + (1 - a) * 0) = a * f(x) + (1 - a) * f(0)。令g(x) = f(x) - f(0),则g(a * x) = a * g(x),即g满足乘法不变性。又g(0.5 * x1 + 0.5 * x2) = f(0.5 * x1 + ... 阅读全文
posted @ 2007-04-18 23:00 quanben 阅读(121) 评论(0) 推荐(0) 编辑