Everlasting Search

New blog on Github pages

2018-03-19T11:18:00.003+08:00

I know I haven't written anything for a long time. But I recently decided to start a new blog using Github pages. Take a look if you're interested: https://hencrice.github.io/

Repost Google Plus Activities to Facebook with a Python app hosted on GAE (Google App Engine)

2013-07-01T09:08:00.002+08:00

A few days ago I found Friend+Me, which is a service that periodically fetches your public posts on G+ and reposts them to other social networks. I immediately signed up for their free plan because Facebook's complicated UI has always been painful to use.

However, the free plan offers only 40 reposts/month so I decided to implement my own version and hosted it on GAE. Since it was the first time I tried out any Google's and Facebook's API, it took me hours to search/go through related documents about GAE, Google Plus API, and Graph API from Facebook. Nevertheless, I still managed to code up a working implementation, check out my G+ profile and FB page (i.e. those posts shared via hencrice_gae). Here's how I've done it:

The whole concept of the program was borrowed from Friend+Me's webpage, only that my implementation is a stripped down, personal-use version of what they offer. That is: (Currently) no repost control with hashtags because all I want to do is merely G+ to FB.

System requirement: Python 2.7 (for deploying your app to GAE). That's it!

1. Go to https://code.google.com/apis/console, create a project. Select "Services" tab on the left and turn on Google+ API:

2. Go to "API Access" tab and jot down your "API key" under "Simple API Access" section:

3. (Optional but highly recommended for privacy reason. I'll explain in step 6.) Create an app on Facebook:

4. (Optional) After creating your app, now's the time to set it up. In the "Basic" tab, write down your "App ID", "App Secret" and "Namespace", then fill in these info and click "Save Changes":

5. (Optional) Then go to "Permissions" tab and type in "publish_actions" then save changes:

6. [ CAUTION: I highly recommend creating your own FB app with steps above to obtain another unique set of "App ID" and "App Secret" because I have made mine public (which should never be done) here. Put it simply, if you authorize the one I created to post on your timeline, malicious users might use this app to post ANYTHING they want on your timeline! ]

Now it's time to authorize the app on FB so that it can post to your timeline on your behalf. First, obtain your FB id with the following:

6. (1) Get your FB username

6. (2) Go to the following for your FB id:

http://graph.facebook.com/FB_username

After that, if you create your own FB app, go to:

https://www.facebook.com/dialog/oauth?client_id=YOUR_FB_APP_ID&redirect_uri=http://apps.facebook.com/YOUR_FB_APP_NAMESPACE&scope=publish_actions

Otherwise, go to:

https://www.facebook.com/dialog/oauth?client_id=467522106672018&redirect_uri=http://apps.facebook.com/publicgptofbwithgae&scope=publish_actions

to authorize the app I created for you guys. It will ask to access your public info and the right to post on your behalf. Beware of the CAUTION clause at the beginning of step 6 :

You can choose the sharing option for the FB app here:

You'll land on this page, just ignore and close it:

You can modify the sharing option later in your setting:

7. Get your Google+ profile ID to fetch your public activities. It should be in your address bar and contains numerical values only. For example,

https://plus.google.com/u/0/GOOGLE_PROFILE_ID_HERE/posts

8. Create an app on Google App Engine https://appengine.google.com/:

9. Now comes the interesting part: Coding! Go here to download App Engine SDK for Python. In this tutorial, I'll use the third one labeled as "Linux/Other Platforms" cause Linux is AWESOME!

10. Extract the zip file and change directory into the extracted folder, create a new folder "GplusToFBwithGAE" (or whatever you like):

11. Download my code https://github.com/hencrice/GPlusToFBwithGAE and unzip it into the new folder you created in step 9:

12. Let's start with app.yaml. For more detail, check here:

13. Next, cron.yaml. There's no need to modify this file unless you want to change the polling schedule of your program (Note that when I was testing, this setting already consumed ~24 out of 28 front end instance hours, which is the daily quota for a free app on GAE). Check here for more details on the schedule format:

14. Finally, the most critical part of our GAE app, GplusToFBwithGAE.py. Fill in variables values at the top:

If you want to know more about how it really works, here are some related documentation:
14.(1) https://developers.google.com/+/api/latest/activities/list
14.(2) https://developers.google.com/appengine/docs/python/datastore/entities?hl=it#Retrieving_an_Entity
14.(3) https://developers.google.com/+/api/latest/activities
14. (4) https://developers.facebook.com/docs/reference/api/publishing/
14.(5) http://stackoverflow.com/questions/7827696/http-post-curl-in-python
14.(6) https://developers.facebook.com/docs/reference/api/post/
14.(7) https://developers.facebook.com/docs/opengraph/howtos/publishing-with-app-token/

15. Open terminal and change directory to the folder in step 10 (i.e. google_appengine), type in the following command (might need to replace "GplusToFBwithGAE" with yours) to upload and deploy your app to GAE (check this for more detail):

python appcfg.py update GplusToFBwithGAE/

16. Go to https://appengine.google.com/ to check whether your app hosted on GAE is running. Now you can either click on the small link beside "Running" to perform an initial setup, which merely set the last polling time as current time, or you can wait a 2~3 minutes (depends on your schedule in cron.yaml) for cron service to automatically set it up for you:

17. Testing your app by posting something public on G+ and check whether there's a similar repost on FB:

Yeah~ You made it :)

海軍新訓結束啦！

2012-10-13T09:15:00.000+08:00

6/26下午5點結束我在成大最後一次，最後一科：演算法，的期末考試後，就跟老爸和老媽開車北上回家。在家裡睡了一晚，隔天早上就在板橋車站搭接近10點的入伍"慢速"自強號專車往左營前進了。因為海軍的新訓中心只有一個，所以火車沿途又停靠了幾站把其他縣市的一些役男接上來。

前幾天的生活真的只能用"忙亂+流汗流到快乾了+被罵到臭頭"來形容，因為我們花了好幾天關在悶熱的建築內不停的填資料，然後領了兩大袋的裝備，再加上新訓中心為了防止感冒大規模傳染，所以規定所有兵都要戴著口罩，在這麼悶熱的情況下，每天流汗應該可以用公升來算了:) 至於被罵的部份，排隊，整隊，走路對腳步，吃飯，洗澡，睡覺沒有一個沒被罵的。

給海軍新兵的一些提示：

帶個小筆記本進去吧，差不多是可以放在口袋的大小。先把12個朋友的聯絡資訊，含居住地，手機等等查好寫在上面，進去填資料時會用到。
也帶個口袋大小的小皮包進去吧！洗澡睡覺都帶著，因為很可能被偷，一旦不見，幾乎都是找不回來的。
自己隨身的行李不要帶太多，而且行李袋越小越好，因為第一天領裝備會抱一個頗大的水兵袋，若你又拿個要拖的行李箱，會超級難移動的。
有些公所兵役科的人員會亂講，說什麼有照相功能的手機也可以帶，其實只能帶最基本的款式，沒有儲存功能(記憶卡之類的)的那種。
徵集令之外所附的一張單子上會寫一些要帶的東西，其中有說要帶照片，要記得帶否則還要爸媽或朋友寄去，會很麻煩因為剛開始若沒有手機，只能打公共電話，很多人排隊所以講什麼都很趕。
剛開始一兩個禮拜會頗有壓力，因為要弄的東西很多，所以做什麼都會很趕時間，之後則會無聊到爆，剛開始先忍忍吧。

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我現在已經下部隊兩個月了，之前寫了這篇忘了po，因為原本想要寫更多真正紀錄我感覺的stuff，但最近實在太忙了~ so就先貢獻給之後要入伍的人吧! See ya~

Sorting integer array in place, in linear time

2012-04-12T11:09:00.001+08:00

Recently when I was learning algorithms, I came up with a pretty handy sorting method that can sort integer array in place, in linear time under the assumption that all the elements in input array are distinct and their values are 1~n(or 0~n-1) where n is the length of input array. So I decided to write a reminder to myself.
Here's the algorithm:

1:  gonnaSortIndex=len(array)-1  
2:  for i=len(array)-1;i>0 {//Note that there's no i-- here
3:    correctIndex=array[gonnaSortIndex]  
4:    if correctIndex!=gonnaSortIndex {  
5:      array[correctIndex],array[gonnaSortIndex]=array[gonnaSortIndex],array[correctIndex] //swapping array[gonnaSortIndex] into its final position and place the swapped out element array[correctIndex] into array[gonnaSortIndex].  
6:   } else {  
7:     i--  
8:     gonnaSortIndex=i  
9:   }  
10: }

This algorithm is clearly in-place, now let's examine what's the possible worst running time~

Although not 100% sure because I did't really prove it but I think in the worst case, the running time is 2(n-1) where n is the # of elements in array
Here's the worst case(that I came up with so far):
Assume we swap all elements into their correct positions while i remains len(array)-1 all the time, so that it will take n-1 times executing if clause on line 4. After that we spend n-1 times executing else clause on line 6 so total running time is: 2*(n-1).
If there's any mistakes, can someone please point it out cause I'm eager to know whether this actually works in all situation under the assumption above.

"我們經不起一次核災: 政府不回答，也不希望你知道的52件事"讀後感

2012-03-10T20:33:00.000+08:00

這本書是一位旅日作家劉黎兒所寫的。雖然，她並非核能方面的專家，但在日本311核災後，她開始嘗試了解核電，並發現到核電並非一向支持核電的日本政府所歌頌的那樣完美。所以她以一個避難者的身份，對仍然擁核的她的故鄉：台灣，發出深沈的警告。

民眾和媒體都是健忘的！日本311核災到今天即將屆滿一週年。現在全世界一片歌舞昇平，全都沉醉在Linsanity的魅力中，好像一年前發生的核災已經不復存在了。沒錯！Jeremy Lin的例子的確是很鼓舞人心，但是這個世界難道沒有其他遠遠比NBA球星更重要的事情需要我們來關心嗎？日本政府聲稱發生事情的原子爐溫度已經穩定下來了，但根據書中所引述的專家看法，溫度降下來是因為爐心已經熔出圍阻體外部進入地下了，換句話說，污染已經不只在核電廠內部，而是擴散到福島的土地，地下水，情況可以說是已經到了無法挽救的地步了。

然而，在整個事件中，最令人吃驚的不僅止於東電在發生事故時的隱瞞，而是在危險曝光後，日本政府的處理方式：簡言之，為了避免相當於日本十年國家預算的醫療，產業賠償以及徒勞無功的除污的費用。即使當地農民表示他們種的作物自己都不敢食用，但因為日本政府公然地違法調高農產品的輻射劑量數十甚至數百倍，使得福島農民所栽種的農作物，以及利用當地落葉等製造的肥料，都仍然無限制地擴散到全日本。而且因為政府無力搬遷所有應避難的居民，所以只好未經修法就調高人體所能忍受的輻射劑量幾十倍，福島當地有能力搬走的居民都已經避難了，剩下的人因為經濟能力等因素無法逃離，只好留在當地繼續呼吸受污染的空氣，食用受污染的農作物和魚肉。許多福島孩子們？」「我將來能不能生小孩？」，被我們視為生命中理所當然的事情，對他們而言變成了奢望。有能力離開當地的家庭的孩子們也不是毫髮無傷，許多地方因為害怕輻射已經開始排斥福島人，即使專家出面呼籲輻射並不會傳染，但福島兒童在其他地區學校被霸凌的案件仍層出不窮，有些餐廳和旅館仍拒絕福島人進入消費。

有別於傳統媒體時常受到各方勢力的影響，網路世界一直被視為能夠自由抒發意見以及闡述事實的一個重要媒介。然而最近一兩年，美國及國際上的一些法案，如SOPA, ACTA等等，都引發政府權力擴張，以至於侵犯言論，自由及隱私權的疑慮。假使如此的法案通過了，一旦發生如日本核災的狀況，政府公然違法時，傳統媒體因受到壓迫而噤聲，網路自由又不復存在，所有能夠得到真相的媒介都已經喪失了！人民的生命財產，對受到強大壓力下的政府而言，只不過是數字罷了！

311核災後，世界上絕大多數國家都決定暫緩興建中的核電廠，並且商議運轉中核電廠的退役事宜。反觀台灣，即便該型號反應爐的原設計者早已經向奇異表示該設計有重大瑕疵，台電仍執意興建核四。再加上台電自行變更了幾百處的設計，並使用全世界最為複雜的控制系統，也使得核四的可靠度十分令人存疑！

台電和台灣政府目前使用的理由，是因為電力不足，所以必須啟用核四。先不論該說法是否為真，請問政府有問過人民，是不是願意犧牲部份時間的電力使用，來避免核四的商轉嗎？沒有！請問台電和政府有對一旦發生事故做好準備嗎？沒有！先不論核電廠週圍的緊急避難圈應該是5公里，50公里還是100公里，緊急避難圈內必備的碘片，我們的里長竟然只有碘藥水，其他就更不用說了。面對可能的災害，我們的準備可以說是趨近於0。難道真的要等到發生核災，全島一起滅亡的時候，才要後悔嗎？

Future

2012-02-25T22:50:00.001+08:00

Forerunner of the path I chose?

The following is what I wrote but stayed as draft until now at the beginning of the fall semester 2011:

"
It's kind of exciting and sad at the same time to see so many new faces in our department, which constantly remind me of the path--the one I chose when I was still a freshman--that seems bumpy all the way down, impossible to penetrate like the muzzy night fog. Nevertheless, I know that the choice will eventually be worth the struggle.

Recently I read a blog post, in which the author cited a quote:

"The man who was crazy enough to think he could change the world, was the one who did"

I'm about to begin my journey, which I have no idea how and when it's gonna end. But still, that won't stop me from striving to be whom I've always wanted to become."

Now I've traveled a fairly long way down the path, it seems like I'm finally getting close to the crepuscule after this long journey in the night. Let's hope that one day I'll get to see the clear blue sky and together we can make a difference, we can change the world :)

Evitable Human Error That Leads To Transplants from AIDS donor

2011-08-29T21:45:00.002+08:00

This is probably one of the worst thing that could ever happen to a person, both from the recipients' and the donor's perspective.

The striking incident arose from one of the most prestigious medical school in Taiwan: National Taiwan University Hospital. Due to bad communication between the examinator and the coordinator in NTUH, the surgeons from both NTUH and National Cheng Kong University Hospital accidently transplanted a few organs of a donor who was infected by AIDS into some patients. Additionally, a few dozens of medical personnel were exposed to large volume of body fluid of the donor without proper protection. Currently, almost all the related personnel are undergoing preventive treatment in the hope to reduce the possibility of being infected. However, the chances of miracle for the recipients now seems rather low because of the tremendous number of AIDS viruses exchanged in the process of and after the transplants.

Such shocking medical error dramatically defiled the reputation of NTUH. It clearly revealed the fact that some doctors and medical personnel in the current system are actually unqualified, mainly because some of the routines and protocols that should definitely be followed were not properly abided by the people involved, which indirectly indicates that some part of the current medical system are seriously flawed, and no one is willing to revise it until such a tragedy happened.

The donor's family is not in a better situation either. According to the donor's mother, she was aware that her son was a homosexual, but she had no idea that he was infected with AIDS. They donated his organs in the hope to save other people's lives, but were sadly informed that their goodwill ended up causing more tragedies.

IMO, both the management and surgeons of NTU should be blamed because they didn't grant enough respect to both the donor and recipients. What we really need is a revolutionary reevaluation of the current medical school admission system, which currently only accepts those with highest test scores rather than those with the eagerness to save other people. I believed that to increase the percentage of so-called "good" doctors, the restriction on admission should be slackened as much as possible, but the requirements for graduation must be far more taut than current standards, so that every student with a passion to save the patients can be admitted, but only those qualified can graduate. This policy will not only change the blindly pursuit of medical schools that many Taiwanese possessed, but also increase the amount of "true" doctors.

針對真愛聯盟的反思

2011-08-16T23:36:00.000+08:00

This post relates to a recent debate in Taiwan so I'll write in Chinese.

因為七月初的時候很忙，所以一直到七月中吧？看到"真愛聯盟退出公聽會"的新聞才注意到這個事件，而最近看到的一些資訊又讓我有了點reflection。首先，我想要聲明我目前並沒有任何的信仰，在短時間內也不打算加入任何宗教團體，單純只是陳述我的看法。

google到真愛聯盟的網站後，看了網站上的性教慾影片，感覺十分驚訝！教育部的人難道是腦袋洞多到跟Cheese一樣嗎？那不然怎麼會提出這麼爭議性的教材？所以，帶著這樣的想法，我把三本教材都下載了下來，並針對真愛聯盟提出疑慮的一些地方看了一次，也大略瀏覽了三本書中其他部份，而我必須說，某些地方確實並非完美(不過，何謂完美本來就是主觀的)，但整體而言我認為它們至少強調了："尊重"和"了解"兩個普世的價值，所以雖然不符合全部人的期待，但至少是個好的開始。

可惜的是，真愛聯盟卻認為這些教材是在鼓吹同性戀(But there's nothing wrong with homosexuals, they are just different, like everyone has different personalities. )，或是贊成青少年嘗試性愛。所以反對它們的使用。而在後續的一些訊息，可以看出真愛聯盟背後似乎有些基督教團體的支持，所以針對那些"激進"的基督徒，我也有些想法：

雖然，基督教的"部份"教徒們的確對世界做出許多美好的貢獻，但"某些"基督教徒的排他性，或者說是偏狹簡直讓我覺得已經到達不理性的程度，例如：為何其他人所經歷的神/神跡都是假的，而只有你們體驗/傳誦的才是真的？你們可以接受一個殺人犯的告解，卻不能接受一個沒有傷害任何人的同性戀？

我寧願相信如果有神的話，祂會以任何的形式來引導我們，而並不會只存在於特定宗教內，而且一定是愛著所有人的！所以一定不會樂見我們因為彼此的不同而互相傷害。我們的不同是為了讓世界更多采多姿，絕非造成更多仇恨！

最後，給那些反對同性戀的人們：當你/妳大聲地批判，以言語甚至肢體傷害同性戀的時候，請想想，若你最至愛的人們中，有人也是同性戀，你/妳會怎麼做？

Regional discrimination: College Students With Big Mouths And Shameful Mindset

2011-07-25T23:56:00.001+08:00

Recently on a popular talk show(an alternative term for garbage, IMO XD!) aimed at college students. They made a whole episode focusing on the difference between young females from northern and southern Taiwan. And the whole episode is filled with discriminatory bias on the style, taste, accents... of southern young females, which provokes thousands of viewers from both northern and southern Taiwan. The existence of this kind of topic clearly reveals the arrogance and shameful mindset that many Northerners possess.

These fools are not the only people who thinks they are superior to Southerners because I've heard controversial statements made by some of my classmates in high school in Northern Taiwan, such as "I don't want to go to college in Southern Taiwan since they're probably political maniacs that might beat me up since I'm a supporter of the other party.", which in reality, is complete nonsense. And the truth is: The classmate that made this statement is himself a politics enthusiast who hates everything, whether it's right or wrong, about the Opposition. Not so civilized IMO = =

The only people that should be treated as inferiors are those who create hatred; who ignore or even joking about the suffering of the others; who express arrogance in public issues, and discrimination against compatriots!

Start Reading a Few New Books and Some Unfin ones(2)

2011-07-22T18:54:00.001+08:00

"The Pragmatic programmer: From Journeyman to Master" is the first book I've ever read in this category, namely software engineering, principles that programmers and managers should obey, etc. Currently I'm only at ch2 but I did learn something all the way up. Additionally, the book was written in a noncontiguous manner that each section is independent, so you can quickly skip to any topic.

"Code Complete 2nd ed" is another book that I'm reading. Compared to "The Pragmatic programmer: From Journeyman to Master", this book seems a bit formal and more specific about the details, such as the naming of variables.
IMO, PP mainly focus on those principles that a programmer should follow while CC2 put its emphasis on the specific details of constructing programs.

I went to see Harry Potter on the day before yesterday with my brother and cousins. Although someone might consider it as the best in the whole series, I think it's a complete waste of money since the so-called "war" between Death eaters and Hogwarts is short and nothing dramatic happens(probably because I've already read the book). Every actor/actress in the movie wields their wands like some maniac and it automatically cast spells to attack the enemies. I can't help but think it must be kind of funny and extraordinary to see these whole bunch people wielding branches on the set without the visual effect of casting spells :)

Start Reading a Few New Books and Some Unfin ones(1)

2011-07-17T23:22:00.001+08:00

I started reading "Introduction to Algorithms" a few days ago and it turns out to be pretty interesting, especially when you don't need to cram stuff for exams in a brainless way! Despite that, by studying algorithms, I can be a better programmer/thinker instead of a translator from human languages to programming languages.

Another one that I'm dipping my feet in is: "C++ Primer 4th edition", which is a 913-page book that can be used as a murder weapon to crack someone's skull(my dark&evil side is looming out of my subconsciousness...). Nevertheless, I have learned C and Java in freshmen year and used them in a few courses later on so learning C++ is not as hard as it sounds, I supposed.

There are a few books that I haven't finished for a long time and some others that I'm currently reading, which I would like to share in another post.

A Diary-like Series? Metaprogramming and Cython for ToDaY

2011-07-16T21:23:00.007+08:00

I'm planning on starting a diary-like series so my general writing skills can be improved. The main problem here is that I spent most of my summer time coding, reading books, exercising and sometimes have my wisdom tooth removed XD, so there might no topics that worth writing about. But I'll try my best to come up with something everyday or at least every other day.

Yesterday I found a brand new(at least for me) idea called: metaprogramming, and it basically means writing programs that can generate/modify programs or other complex files(for instance, configuration files). This is pretty inspiring since both programmer and programs coded can achieve state-of-the-art performance, and still remains abstract for high-level interpretation. Gonna dig out more info on this topic after reading this paragraph from IBM: The art of metaprogramming, Part 1: Introduction to metaprogramming

Besides, I used Cython for the 1st time in my personal lab project to boost the performance of my program and I'm impressed! It makes everything I modified at least 3x faster even for trivial stuff! Brutal speed from the CPU directly :)

Damn! This post is starting to become a nerdy review on the new toys I've been playing so I should probably stop now! See ya tomorrow!

What I've Been Busy Doing

2011-07-02T07:46:00.006+08:00

I notice that I haven't written anything since March. What the hell?!

Alright, here's some stuff I've busy doing:
(1)A TCP chatroom program including a client and a server comunicating via a "home-made" protocol. Additionally, you can private messaging anyone in the chatroom.

src code here: https://bitbucket.org/hencrice/tcpchatroom/wiki/Home

(2) Add a stupid system call to the Linux kernel and compiled it, then booted my laptop from it.

Image via Wikipedia

(3) Days and hours wasted in assembly coding, which in short: "Write more do a lot less and get bored" ! But I did learn something though.

(4) Built a Lego robot which is the fastest in my class to walk through a maze. I wrote all the code through out the course. AWESOME experience!! And I learned that mechanical structure is essential for robot "programming", that is, software and hardware must cooperate together to make a robot a good robot!!

(5) Reading papers for my lab project.
Info on papers: http://info.ee.surrey.ac.uk/Personal/Z.Kalal/tld.html
Writing some code... ongoing work

(6) Read through Python essential reference

(7) Made an AWESOME paper airplane and watch a few movies in a course I took in dep. of Aeronautics and Astronautics

Marry Me by Train

2011-03-06T21:32:00.005+08:00

This SOO beautiful! Wish that one day I'll have the chance to say the same to a girl. And my ultimate "job" is to see her smile: )

Why Python Rocks?! From A Newbie's Viewpoint

2011-03-04T16:18:00.008+08:00

Image via Wikipedia

Learning Python is the most pleasant experience I've ever had in learning a new programming language. Although I had some experience in both C&Java, I'm neither master of the 2 languages. However, I found that it was pretty easy for me to pick up Python. Here are some key characteristics:

(1)Coding performance: Basically, I don't really need to transform my thoughts into something overly abstract, which is often needed in Java and C. As a result, you can think/write the code at the same time, which boost your coding performance.

(2)Powerful and easy-to-use GUI: I personally love PyQt4 since I dabbled in Python after Python3.1 was already released, and PyQt4 is the only GUI library which fully supports Python3.X. Although this is definitely subjective, I really hate Gtk+ for its complexity(I had learned it for a short period of time).

(3)Ability to define function/class within function/class: I think this will leave an better overview to the programmer who reads or uses your source code since they don't need to go through every function(some of them are just helpers) you defined.

(4)Readability:This is probably the side effect of great coding performance. I found that even for a Python newbie like me, it's still very easy to understand some code which was written a long time ago.

There will be more...

Feeling Like I've Lost Something Precious

2011-03-03T21:42:00.001+08:00

Honestly, I'm not really sure what's missing in my life.

"Time" probably?

I know this may sounds strange for a young folk like me, but whenever I encounter some people who are really talented&diligent, I can't help thinking that I seemed to waste so much time in my adolescence cramming stuffs, which were needed to get me here(as a college student) but now completely useless. For instance, I memorized the rules for composing ancient Chinese poetry in 8th grade, but I've never been in the mood to appreciate the beauty of any poem. Don't get me wrong, I love reading, except those advocating doctrinaire dogmas, and that whole thing written in a dead-elusive ancient language just make it worse.

I think I'll definitely do a better job at what I'm interested in now if I had the time to explore and learn freely when I was a teenager: playing keyboard, dancing, these are things I kind of giving up(due to lack of time), and programming, which I'm pretty good at, but hasn't reached mastery.
As the time passed by, I found that it's getting harder and harder for me to spend time on things I really want to. Pretty sad huh?

Mathematica Fun"s":Solving Electromagnetic HW4 Prob2

2011-01-17T09:19:00.021+08:00

Question:

Write a program, based on finite difference method, to find the Capacitance per unit length of the following structure, accurately to three significant digits. The conductor at the center has a width of 2w. The conducting enclosure is 9w in width and 5w in height, as shown in the figure. The structure is infinite in extension perpendicular to the page.

pictures in my report:

This is the 2nd program I wrote this semester, since I became more familiar with writing Mathematica code then so the efficiency is much better despite the fact that the 2nd program was more complicated than the 1st one. I still remember that I spent days writing this program&document and felt exhausted afterwards XD!
Here is my main idea of the program: Assume that there will be 0.04 nano Coul on inner conductor and -0.04nC on outer conductor, using the concept of superposition
(1)Take out -0.04nC on outer conductor, using moment method to calculate the voltage(Vin1) induced by +0.04nC on inner conductor. After that, use finite difference method to calculate the voltage(Vout1) induced by +0.04nC on outer conductor.
(2)Similarly, take out +0.04nC on inner conductor and use moment method+finite difference method to find out the voltage(Vin2) on inner conductor and voltage(Vout2) on outer conductor, both produced by -0.04nC.
(3)The real value of voltage of inner conductor Vin=Vin1+Vin2, and the true voltage of outer conductor is Vout=Vout1+Vout2
(4)Capacitance per unit length=(0.04nC/cm)/(Vin-Vout)

The main question I had for this program is that I'm not 100% sure that I can use superposition to calculate the voltage(i.e. Vin1,Vin2,Vout1,Vout2), since the steady-state charge distribution on either inner or outer conductor will be affected by charges on both of inner&outer conductor. But I tried to present this effect by step (3), so it should be ok(it should be Okay!?).

Note: Be ware!! The result I got from this program was 2 times what one of my friend got, so I'm not really sure which one of us got the correct result since we use 2 totally different methods.

The report in Mathematica:
http://www.megaupload.com/?d=GJA8CELZ
The report in pdf:
http://www.megaupload.com/?d=K7IBHMR6

Mathematica Fun"s": Solving Electromagnetic HW1 Prob1

2011-01-16T22:43:00.003+08:00

Prob1:
A conducting thin wire has a total length of 4 cm and is bent into a square with its
center at the origin. There is a total of 4 nano Coul of electric charges on it. Use moment method to find the potential of this wire V, accurately to the second digit of decimal. (You must carry out all the calculations. Just list out equations will get you no points)

The main idea of this program is pretty easy: Using finite number of charges of various value to approximate the continuous charge distribution on the square conductor shown in the following figure:

The hardest part of this program is to build up the matrix to be solved.
(1)Calculate the position of charges on 4 sections of wire based on the user define value: n(shown in the picture above)
(2)Calculate the position of observation points on the X axis which also based on the user defined n.
(3)Calculate the voltage on each of the observation points.
(4)All the values of calculated voltage should be the same otherwise it won't be stable and will lead to currents on the conducting wire that result in the true stable state. Solve the matrix consist of n*n 1st-order equations
(5)Use the charge distribution gained from step (4), calculate the steady-state voltage of this wire.
That's ALL!

p.s. this is the 1st program I've ever written in Mathematica at the beginning of this semester, so please forgive me for the crappy coding style XD. Due to my unfamiliarity with Mathematica, the efficiency of this program wasn't very good,either! Sorry guys!

readme file: http://www.megaupload.com/?d=3SULVG4Q
main program: http://www.megaupload.com/?d=L5V5VCIJ
the graph showing the converging results: http://www.megaupload.com/?d=USLLAK6E

Most Exhausting Semester I've Ever Had in Past 3 Years Was Over

2011-01-14T23:57:00.002+08:00

I'm just glad that this semester is finally over! After the torture of final exam of 6 subjects(in 4 days!!), we, students of EE, can finally embrace the longing winter vacation that we've been hoping for.

Honestly, I learned a ton in this semester, but that also means I have to take many exams, which leads to an endless nightmare of brainless activity called "Memorizing a bunch of stuff even if you already understand them"! Sadly, for particular 1 subject it was even worse, since the professors tried to teach too much things in such limited time, which resulted in lightening-fast lecture speech and getting most of the students into what I called "DKWHYTHT" mode or even fell asleep=>**DKWHYTHT stands for "Don't Know What the Hell You're Talking about Half of the Time".

But at least I did find out that I'm really into robotics since I found that I enjoyed the control theory class this semester.

p.s. I found a great tip to keep myself from being pessimistic under pressure: Try to focus on the thoughts about how happy and relaxed you'll be after going through all the stuff you hate.

Mathematica Fun"s": 3D "Merry Christmas" In Jokerman Font Using Plot3D And Image Processing

2010-12-13T19:59:00.002+08:00

Merry Christmas! : )

It took me a few days to finish this notebook in my free time! Mostly spent on manually taking each character out of the original picture which contains all the capital and non-capital alphabet.

The original picture of Jokerman font found on the web:

(1)The easiest step: Find the font you want on the web

(2)Use Binarize[ ] to create a binary(0 is black,1 is white) image of the original picture. After that, use ImageTake[ ] to take out each alphabet.
The 2 binarized images:

(3)Use ImageTake[ ] again to take out each alphabet and use ColorNegate[ ] to create figures like the following:

The reason for using ColorNegate[ ] is because I will use the value of each pixel as the z value in 3D space (x,y,z), so color white indicates z=1, color black indicates z=0.

Note: If you use drawing tool to modify your pictures, remember to Binarize[ ] the modified pictures again even if the color you use in modification is the same as the color on the picture or Plot3D will take forever to draw the result!!

(4)Use ImageDimensions[ ] to measure how many rows and columns of pixels in each alphabet.

(5)Use a list as a container to store these data(alphabet figure, its' dimensions) into corresponding variables. For instance:

(6)Thanks to the new Texture[ ] function in Mathematica 8, it's very easy to apply texture on anything you drew, whether it's 2D or 3D.
2 images of plastic texture I found on the web:

Set up the following function:

Comment: use ImageValue[ ] as the function to be drawn by Plot3D[ ]

(7) Use the function and produce a single character:

DA LA!! You got A! Good job, dude!!

If you want to create a series of characters like the picture at the beginning of the post, just use Map[singleC,{W,o,r,l,d,P,e,a,s,e}], or singleC/@{W,o,r,l,d,P,e,a,s,e} will also do the job. I have built data for all non-capital alphabets but not all capital alphabets, you can do that easily in my notebook since I list out all the functions I used.(Beware that some capital alphabet are built-in symbols of Mathematica so they're protected.)

Here's the link for you to download the notebook:
the main program
http://www.megaupload.com/?d=RH97O32C

the output of singleC[ ] using "Merry Christmas" as arguments http://www.megaupload.com/?d=Q488CC09
p.s. If you find the links are not working or the download speed is a disaster, feel free to leave a comment: )

Mathematica Tips: Controlling Accuracy And Precision Using N[ ]

2010-12-10T21:14:00.002+08:00

Although the equations in every textbooks are mostly exact and in closed form, we all know that measurement errors actually play a vital part in practical situations. During the course "Electric Instruments And Measurement" this semester, I learned that even with some highly-optimized electric devices, the results of measurement are still questionable if the devices are operated under "wrong" conditions. And that's why the difference between "Accuracy" and "Precision" does matter.

First of all, I want to clarify the difference:

Accuracy: Based on Wikipedia and what I've learned in class, accuracy is "the degree of closeness of measurements of a quantity to its actual (true) value."
Precision: Degree to which repeated measurements under unchanged conditions show the same results.

To be more specific, here are some figures:
(**Note:the vertical axis is % in total number of measurement, the vertical line indicates the actual value)
(1)poor accuracy good precision

(2)good accuracy good precision

(3)poor accuracy poor precision : (

(4)good accuracy poor precision

After the clarification, we can now finally focus on:
N[expression,{precision,accuracy}]
Let's see a few example and explain them

(1)precision>accuracy
-----------------------------------------------------------------------
-----------------------------------------------------------------------
When using N[ ], you can think of it as you're "measuring" the actual value, that is 1/17, which is an exact number. So if you only asked Mathematica to "measure" the result with accuracy 4,but wanted it to display result as precision 13, it won't show that many digits cause the additional digits won't be correct(unless you want to mess up your calculation and end up with nonsense).

(2)precision<=accuracy
-----------------------------------------------------------------------

-----------------------------------------------------------------------
Now Mathematica is willing to display more digits since it has "measured" 1/17 with higher accuracy so now it's confident that the displayed result is correct.

p.s If you guys see any errors or stupid things I did in coding or explanation, feel free to correct me in the comments: )

Conrad Wolfram: Teaching Kids Real Math With Computers&Reflection On College Education In Taiwan

2010-12-07T21:27:00.005+08:00

Almost every education reformation started as "The current education system is not suitable for the future generation!", "We need to teach our kids "portable" knowledge!"

Unfortunately, worse than what Mr.Wolfram said at the beginning of the video, I think "We got a real problem with college education right now!" will be suitable for describing the college education system here in Taiwan based on the past 3 years I had as a student of EE.

What Mr.Wolfram presented in this talk is definitely refreshing. He did pointed out a few really important factors in existing education systems:

(1) Dumb down the questions so that we students can solve them by hand. Yes...By hand! And maybe a little help from an engineering calculator which is often useless except doing stupid and straightforward calculation(i.e. IC=Is*e^(Vbe/Vt)... that sort of things).

(2) Spend most of the time doing/teaching students how to do the calculation rather than the process of how to construct appropriate equations to be solved, how to verify the calculated results, and most important of all, the limitation of everything you used in the process.

To make matters worse, I think we got a bigger problem in Taiwan(and maybe other countries) due to what most college students need to get into graduate school: Another test...and that implies tons of stuff to memorize! After spending years in our adolescence cramming and memorizing stuff that you immediately forgot after the test, why the hell to we need to repeat all that stupid routine again as a college student? As the result of this brainless system, the teaching style of professors must change accordingly, so do the way of midterms are held in schools. (It might need a 10-page long essay to discuss why college students here "must" get into graduate school so I'll just leave it out.)

For example, to prepare for the midterm of most subjects in EE department:
(1)read through the text, class notes and handout to fully understand the concepts.---------------------->An interesting process and really helping the students!

(2)Instead of practicing exercises or problems provided, we students need to memorize equations and some properties, cause none of them will be provided in the test, and you won't have time to derive them from the concepts due to the 2-hour limitation of midterms------------------------->A STUPID and brainless step which require pretty much no or few intellectual activities in our brain.

(3)"If" we have time left, we can finally start working on the exercises and problem sets.

Based on my experience(I'm some sort of hard-working type so I study everyday),
the time left for step 3 is often approaches 0, cause most of the time was taken out in step 1 and 2. But step 3 is actually much more important than step 2 for any future engineers cause that's what we will be doing in our career! We solve real-world problems!! And step2 shouldn't even be a "step"!

To be more precise, if you already gone through the text(i.e. finish step 1) and there are 7 days left before the midterm of a subject(that often happened on us,what just taught this week will be on the midterm next week), you'll still need to spend at least 3 to 4 days memorizing everything you already understand! What if there are midterms for 2 subjects or even more next week? A:You'll end up spending all the time memorizing things for 2 subjects and got very less time for step 3.

Okay! Now it comes to how do we prevent the brainless step2? The answer is obvious: the way of midterms are held and how we enroll the grad school should be changed! A great living example will be the course I took this semester: Analog Communication. The professor allow us to bring in a double-sided notes which contains equations, properties, but no solutions to any homeworks or problems in textbook(A few TA are responsible for checking the notes right after the exams). This is great cause I can now spend my time on something more creative than cramming stuff into my brain.

Sadly, there's no sign of changes to this brainless system so far. I can only try my best to learn.

2 New Catagories For Mathematica:Tips&Fun"s"

2010-12-07T19:24:00.003+08:00

Image via Wikipedia

Although I've been using Mathematica for about 5 years now, as I mentioned in my previous post, not until recently(Uh..actually, at the beginning of this semester) did I discovered and started to realize the potential of Mathematica. So I think I perfectly fit into the "newbie" categories.

As the title says, I'm going to start 2 new categories to take down all the things I learned in/about Mathematica, and most important of all, the fun time I had using it.

The 2 new categories are:

(1)Mathematica Tips: For all the tips I came up with or learned from other programming masters.

(2)Mathematica Fun"s": Some interesting problems or things I solved using Mathematica, for ex: Electromagnetics HW problems, Control Theories class...
There will be a post for some tips after the analog communication midterm on Thursday.

I think I'll provide pdf and Mathematica notebook files for each post if you're willing to spend time on my crappy code : )

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Mathematica 8 Is Full Of Surprises!

2010-11-20T17:16:00.120+08:00

Since it's the coolest tool I've ever seen, so I can't help spreading the new idea.
Here's more detail, enjoy!

I still remembered the 1st time I used Mathematica when I was only 16.
The version 5 of this software was introduced to a group of high school students in a short-term course held by my math teacher. Honestly, due to the lack of experience in practical problems, I didn't realize how powerful it was. For me it was merely a "really cool calculator" then. The thinking never changed until taking Electromagnetics this semester, where I learned some powerful numerical analysis methods and actually implemented/presented them using Mathematica, which was sort of brand new and exciting experience for me, since I've never used any kinds of 4GL before. Now it has became a tool that I use almost everyday to solve problems and help me understand the concepts in lectures by visualizing them.

Typhoon, School Closures: Another Perspective

2010-09-20T10:39:00.005+08:00

Whenever there's a blizzard or typhoon or any natural disasters, we student often expect a day off, and 2 will be even better! But it never really occurr to us that it is NOT just simply a day off, it came with a price: People will lose their property or even lives, economy will also temporarily suffer from the catastrophe.

When you look at a satellite image like this, you'll probably say something like, "Wow! The storm is huge! Look at the size of it! I wonder when the authorities will announce a day off?" Sadly, few will think in another perpective, "There are many people down there, hope they will go through this safely."

When I was a kid, I used to hope that the typhoon will come so that
I would have an extra day off. But my parents told me I shouldn't think in that way cause no natural disaster will leave without any damages. So I realized that hoping the typhoon to come is the same as hoping someone to get hurt, the only difference is that you probably won't know the person, but that doesn't make it right!

Many of my friends prey for the school closure last night, and I really hope that one day they will realize how wrong it was, just like me when I was a kid. If anyone who knew the fact but still want the typhoon to come so that they will have a day off while others suffering, he/she will be a selfish jerk!