生成m行n列的独立随机信号:R = 1 - 2*1*rand(m,n)如要在[-a,a]之间生成，则为R = a - 2*a*rand(m,n)例：R = 1-2*1*rand(1,10)R =0.8481 0.5202 0.7534 0.6322 0.5201 0.1655 0.9007 -0.8054 -0.8896 0.0183.
