matrix square root
y = sqrtm(x)
a real or complex square matrix.
y = sqrtm(x) is the matrix square root of the x matrix (x=y^2). Result may not be accurate if x is not symmetric.
x
x=y^2
x=[0 1;2 4] w=sqrtm(x); norm(w*w-x) x(1,2)=%i; w=sqrtm(x);norm(w*w-x,1)