跟我一起写makefile（epub版）

可以在多看pad或者手机上看，非常方便。

软件工程 software

1. Web sections These are extra sections that add to the content presented in each chapter. These web sections are linked from breakout boxes in each chapter. 2. Web chapters There are four web chapters covering formal methods, interaction design, documentation, and application architectures. I may add other chapters on new topics during the lifetime of the book. 3. Material for instructors The material in this section is intended to support people who are teaching software engineering. See the “Support Materials” section in this Preface. 4. Case studies These provide additional information about the case studies used in the book (insulin pump, mental health-care system, wilderness weather system)

Fast sparse matrix multiplication

最快的稀疏矩阵乘法运算，英文版 Let A and B two n £ n matrices over a ring R (e.g., the reals or the integers) each containing at most m non-zero elements. We present a new algorithm that multiplies A and B using O(m0:7n1:2 + n2+o(1)) algebraic operations (i.e., multiplications, additions and subtractions) over R. The naive matrix multiplication algorithm, on the other hand, may need to perform ­(mn) operations to accomplish the same task. For m · n1:14, the new algorithm performs an almost optimal number of only n2+o(1) operations. For m · n1:68, the new algorithm is also faster than the best known matrix multiplication algorithm for dense matrices which uses O(n2:38) algebraic operations. The new algorithm is obtained using a surprisingly straightforward combination of a simple combinatorial idea and existing fast rectangular matrix multiplication algorithms. We also obtain improved algorithms for the multiplication of more than two sparse matrices. As the known fast rectangular matrix multiplication algorithms are far from being practical, our result, at least for now, is only of theoretical value.