摘要： 某天看校友网，看到某个师兄说现在的高中教育不行，题目太死板，如果他出题，他会出一道题：如何证明勾股定理a^2+b^2=c^2？当时我觉得这个题目很有意思，不过当时也懒得想。后来某天晚上刷牙的时候，突然想起来这个题目来，刷完牙在纸上画了画，搞定，然后安心睡觉。现在离那时有些日子了，在此记录一下证明过程。如图：正方形ABCD，AE=BF=CG=DH,证明AH^2+AE^2=EH^2.证明：为了方便起见，设AE=a，AH=b，EH=c。因为ABCD是正方形，且AE=BF=CG=DH=a，则EB=FC=GD=HA=b，因为正方形四个角都是直角，所以三角形HAB，EBF，FCG，GDH全等(角和两个夹边 阅读全文

摘要： by Torstan, 2011-10-4 23:08Today I successively add a system call in linux kernel, long foo(), to output the size of per-process kernel stack. The procedure is as follows.step1. add an entry to the end of system call table.torstan@stan:~/code/linux-2.6.24/arch/x86/kernel$ diff syscall_table_32.S.bk 阅读全文

摘要： by Torstan 2011-7-3 13:20In this weekend, I just want to try compiling and installing linux kernel. The root cause is I am a programmer having 3 years working experience. After 2 days, I succeeded. I am so happy. Now I am recording the flow.Before all steps, I describe the environment I used. I have 阅读全文

摘要： http://zh.wikipedia.org/wiki/%E4%B8%80%E9%98%B6%E8%B0%93%E8%AF%8D%E6%BC%94%E7%AE%97 阅读全文

摘要： http://stackoverflow.com/questions/1005169/lua-garbage-collection-of-tables-nested-tableshttp://lua-users.org/wiki/GarbageCollectionTutorialhttp://pgl.yoyo.org/luai/i/2.10+Garbage+Collectionhttp://pgl.yoyo.org/luai/i/2.8+Metatableshttp://lua-users.org/wiki/EmergencyGarbageCollector 阅读全文

摘要： function: let A and B be noempty sets. A function f from A to B is an assignment of exactly one element of B to each element of A. We write f(a)=b if b is the unique element of B assigned by the function f to the element a of A. If f is a function from A to B, we write f: A->B, (we also call it f 阅读全文

摘要： key conceptset: a set is an unordered collection of objects. (It is not part of a formal theory of sets)This intuitive notation will lead to paradoxes, or logical inconsistencies.naive set theory: not develop an axiomatic version of set theory.set builder: the defination of belonging symboltwo sets 阅读全文

摘要： key conceptsproposition: a statement that is true of falsepropostional variable: a variable that represents a proposition, e.g., use p describe propos... 阅读全文

摘要： A professor said, In the west, only those top math depts have logicians, those mediocre ones do need logicians!!A decent program of logic should have 1. Intro to Mathematical Logic; 2. Set Theory; 3. Model Theory; 4. Computability Theory; 5. Proof Theory; and 6. Modal Logic...So I found a famous b.. 阅读全文

摘要： 实验目的：在理解离散小波变换原理和Mallat快速算法的基础上，通过编程对图像进行二维离散小波变换，从而加深对二维小波分解和重构的理性和感性认识，并能提高编程能力，为今后的学习和工作奠定基础。实验工具：计算机，matlab6.5 附录：（1）二维小波分解函数%二维小波分解函数function Y=mallatdec2(X,wname,level)%输入:X 载入的二维图像像数值; % level 小波分解次(级)数设定值(如果设定值超过最高可分解次数,按最高分解次数分解)% wname 小波名字wavelet name%输出：Y 多极小波分解后的小波系数矩阵[h,g]=wfilters(wna 阅读全文