用matlab实现的26个字母识别。基于BP算法的字母识别其容错性和识别率相对较高，在有噪声的情况下训练其识别出错率也相应增加，许进一步改进。(26 letter recognition implemented with MATLAB.The letter recognition based on BP algorithm has a relatively high fault tolerance and recognition rate, and the error rate of recog