替代加密:
A B C D E F G H I J K L M N O P Q R S T U V W 密文
Y Z D M R N H X J L I O Q U W A C B E G F K P 明文
X Y Z
T S V
I HAVE A DREAM！#
密文？？
用ARM編程實現替代加密。
Initialize U=[uij] matrix, U(0)
At k-step: calculate the centers vectors C(k)=[cj] with U(k)
Update U(k) , U(k+1)
If || U(k+1) - U(k)||< then STOP otherwise return to step 2.
