Overprolific Alpha Geeks

Everyone, including Alpha Geeks, use only one app:

People complain about how their work wants them to use organizers…

Joel Splosky uses Excel for everything.

HR person sends website designs in PPT.

Don Lancaster sees the world in Postscript.

— Running notes from

Life Hacks: Tech Secrets of Overprolific Alpha Geeks

— Danny O’Brien

— 11 February, 2004

— by Cory Doctorow

2013.03.03 Sunday ACHK

微積分 6.2

無限年 3.2

這段改編自 2010 年 4 月 3 日的對話。

「爺爺」=「爸爸的爸爸」

」 = 「如果 x 越來越大,1/x 會越來越接近零。」

「\left( \lim_{x \to \infty} \frac{1}{x} \right) = 0」 = 「如果 x 越來越大,1/x 會越來越接近零。」

還有,這一句仍然只是「簡稱」,還未精確到可以視為數學句子。完整的版本詳盡很多。

詳細一點的版本是,

」 = 「只要 x 足夠大,1/x 就會足夠接近零。」

只要具體釐清,在這個上文下理中,何謂「足夠大」和「足夠接近」,你就可以得到「」的正式數學意思。

」 = 「無論 a 的數值是多麼小,你都可以令 1/x 和零的相差小於 a,只要你設定 x 的數值大於 1/a 。」

— Me@2013.03.03

2013.03.03 Sunday (c) All rights reserved by ACHK

Learning physics online?

事業愛情觀 3

   
It always makes me laugh when people hope they can learn physics online. Yeah, sure you can, just as you can learn languages online but you’re not going to be articulate compared to someone that is on a full time course. They live physics for years with like minded people, day in, day out. If you want to learn physics the same way someone learns a foreign language by carrying around a translation dictionary because they lack the effort required, then go right ahead. Just don’t delude yourself in believing you can know what a graduate physicist knows.

Let me put it another way:

A physicist on a full time course might spend at least 50 hours a week learning about physics. How much time do you have to spare?

   
— answered May 25 ’11 at 22:16

— Larry Harson

2013.03.02 Saturday ACHK

Marriage

Process, not a state, 8

.

Marriage is not a single event. Marriage is a lifelong process.

“Married” is not a state, but a process.

— Me@2010.12.24

.

.

2013.03.02 Saturday (c) All rights reserved by ACHK

微積分 6.1

無限年 3.1

這段改編自 2010 年 4 月 3 日的對話。

簡便起見,你可以視「無限份之一」等如「零」。

1/infinity = 0

不過,那只是輔助記憶的密碼,而不是正確合法的數學符號,因為,「無限」並不是一個數字,你不可以用「無限」來運算,或者表達任何數量。正確的寫法是,

\left( \lim_{x \to \infty} \frac{1}{x} \right) = 0

而它的真正意思是:

如果 x 越來越大,1/x 會越來越接近零。

(安:那為什麼不直接那樣說,而要用複雜的數學符號來誤導人?)

因為那句說話冗長,但在數學中又要時常使用。沒有「簡稱」的話,會十分不便。正如,當我們教一個小朋友,「爺爺」是「爸爸的爸爸」的簡稱時,他同樣可以質疑,為什麼不直接說「爸爸的爸爸」,而要用複雜難寫的文字來誤導人?

「爺爺」=「爸爸的爸爸」

」= 「如果 x 越來越大,1/x 會越來越接近零。」

還有,這一句仍然只是「簡稱」,還未精確到可以視為數學句子。完整的版本詳盡很多。

— Me@2013.03.01

2013.03.02 Saturday (c) All rights reserved by ACHK

Backward compatibility, 5

To enjoy the past without limiting your life progress, install the past as virtual machines in the present. 

— Me@2013-02-24 2:50 am

The attraction of virtualizing older operating systems is that it throws off the eternal yoke of backwards compatibility. Instead of bending over backwards to make sure you never break any old APIs, you can build new systems free of the contortions and compromises inherent in guaranteeing that new versions of the operating system never break old applications.

— Has The Virtualization Future Arrived?

— April 26, 2009

— Coding Horror

— by Jeff Atwood

You cannot start a new chapter of your life if you keep re-reading the last one.

The past is a good place to visit but a bad place to stay.

2013.03.01 Friday (c) All rights reserved by ACHK