import pylab
import matplotlib.cm
A=matrix(pylab.imread('/home/cheub/lv/linalg2/Shared/Demo/bild/bild2sw.png'))
m,n=(A.nrows(),A.ncols())
U,S,V=A.SVD()
norm(U.transpose()*U-identity_matrix(m))
norm(V.transpose()*V-identity_matrix(n))
norm(U*S*V.transpose()-A)
@interact
def approx(k=slider(1,min(m,n),1)):
    print("Kompression auf %.2f %%" % (k*(1+m+n)/(m*n)*100))
    pylab.imshow((U.submatrix(0,0,m,k)*S.submatrix(0,0,k,k)*V.transpose().submatrix(0,0,k,n)).numpy(),cmap=matplotlib.cm.gray)
    return(pylab.savefig('test'))