是学习PCA特征提取的很好的学习资料，复化三点Gauss-lengend公式求pi，包括最后计算压缩图像的峰值信噪比和压缩效果的源码。- Is a good learning materials to learn PCA feature extraction, Complex of three-point Gauss-lengend the Formula pi, Including the final calculation of the compressed image peak signa