2011-02-17

rank

請問這題求RANK,有特別的求法?

1 則留言:

線代離散助教(wynne) 提到...

和平常一樣, 就對 A 做列運算可得 R =
1 exp((2/3)πi) exp((4/3)πi)
0 1-exp(2πi) exp((2/3)πi)-exp((8/3)πi)
0 0 1-exp(2πi)

因為 exp(2πi) = cos(2π)+i*sin(2π) = 1
且 exp((8/3)*πi) = exp((2/3)πi),
所以 R =
1 exp((2/3)πi) exp((4/3)πi)
0 0 0
0 0 0
=> rank(A) = 1