아래 일기, 해결했다! 복소수로 형변환!

> a <- matrix(as.complex(c(1,2,3,4,5,6,-1,-2,-3)), ncol=3, byrow=T)
> a.eig <- eigen(a)
> a.sqrt <- a.eig$vectors %*% diag(sqrt(a.eig$values)) %*% solve(a.eig$vectors)
> a.sqrt
[,1] [,2] [,3]
[1,] 0.6137491+0.2418805i 0.7279928-0.4078445i 0.842236-1.057569i
[2,] 1.9554910+0.0759164i 2.3194874-0.1280058i 2.683484-0.331928i
[3,] -0.6137491-0.2418805i -0.7279928+0.4078445i -0.842236+1.057569i
>