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  Revenue = X

We've been experimenting with app prices for quite some time and again and again we've noticed a funny effect:No matter what price we choose, we always make the same revenue.I attached two charts to illustrate that. I recently lowered the price of the iPad app (http://bit.ly/92xWv1) from 5 to 1 Dollars. At first the sales spike, then they even out to previous levels. Meaning: By cutting the price by factor 5, I am selling exactly 5 x more apps. Then we lowered the price of iA Writer for Mac...

   Revenue,Price,Productivity,Investment,Discount,Software     2011-11-17 02:31:58

  20 bit operations programmers should know

While talking about bit operation, programmers usually think about its efficiency. In embedded programming and system core optimization, appropriate use of bit operations is always a fascinating. When finding a job, it will help you a lot if you use bit operations when writing codes. Mastering simple bit arithmetic skills is necessary. 1. Get maximum int value int getMaxInt(){           return (1 << 31) - 1;//...

   Bit operation, Tips     2012-12-19 12:53:33

  How Integers Should Work (In Systems Programming Languages)

My last post outlined some of the possibilities for integer semantics in programming languages, and asked which option was correct. This post contains my answers. Just to be clear: I want practical solutions, but I’m not very interested by historical issues or backwards compatibility with any existing language, and particularly not with C and C++. We’ll start with: Premise 1: Operations on default integer types return the mathematically correct result or else trap. This is th...

   Number,Algorithm,System,Embedded system     2011-12-05 12:48:41

  Tips for improving PHP efficiency

0. Using single quote to replace double quote to enclose string literal, this will be a bit faster. Because PHP engine will search variables in double quoted string. 1. If a method in class can be declared as static, then make it static, this will be 4 times faster. 2. $row["id"] is 7 times faster than $row[id] 3. echo is faster than print, and you should use multiple parameters instead of string concatenation, i.e use comma(,) instead of dot(.) to concatenate string. For example echo $str1,$str...

   PHP, efficiency, tips     2012-10-01 19:39:06

  About tmpfs

tmpfs is another confusing name in Linux kernel, its implementation is in mm/shmem.c, shmem has no relation to tmpfs at first glance although we know tmpfs is based on memory. We can understand why we use this name by seeing where this is used. In a desktop Linux system, tmpfs is loaded usually: % grep tmpfs /proc/mountsdevtmpfs /dev devtmpfs rw,seclabel,nosuid,relatime,size=1958956k,nr_inodes=489739,mode=755 0 0tmpfs /dev/shm tmpfs rw,seclabel,nosuid,nodev,relatime 0 0tmpfs /run tmpfs rw,seclab...

   tmpfs,Linux,file system     2013-06-14 12:10:56

  Mac shortcut key cheatsheet

More and more people are using Mac computers or switch from Windows or other OS to MacOS, there are lots of shortcut keys which can help improve the work efficiency or ease operations. This post will try to list some commonly used shortcut keys in Mac. But before that, let's first know some common keys on a Mac computer keyboard. There are four major function keys: Command, Control, Option and Shift. Most of the shortcut keys will combine the functional key and other key. Basic Command key is t...

   SHORTCUT,SCREENSHOT,COMMAND,SHORTCUT KEY,MACOS     2019-02-05 07:13:06

  Apache Tomcat Installation and Configuration

When you want to install Apache Tomcat on Windows System. You may find that there are some tricky parts. Next I will elaborate the steps to install and configure Tomcat. If you want to install Tomcat as a service without GUI. You need to download the 32-bit Windows.zip from http://tomcat.apache.org/download-70.cgi. After downloading this zip file. You need to unzip this file to the directory which you want to put this software to. After unzipping, you can go to the bin directory and find t...

   Tomcat 7,Windows,Apache,Install,Configur     2011-04-10 14:17:21

  How to optimize MySQL insert statement

For a big data system, one problem is the data access efficiency, one more problem is that the data insertion is very slow. We had a service system, the data loading process would take 4-5 hours. This time consuming operation is risky since if the program is interrupted during the loading process, it might be rerun, this will be troublesome. So it's necessary to improve the insertion efficiency for big data systems. Here we provide two optimization suggestions. 1. Combine multiple insert stateme...

   MySQL,insert,optimization     2012-10-24 22:03:13

  Fujitsu CTO: Flash is just a stopgap

Flash is a necessary waystation as we travel to a single in-memory storage architecture. That's the view from a Fujitsu chief technology officer's office. Dr Joseph Reger, CTO at Fujitsu Technology Solutions, is that office-holder, and – according to him – flash is beset with problems that will become unsolvable. He says we are seeing increases in flash density at the expense of our ability to read and write data. Each shrink in process geometry, from 3X to 2X and onto 1X, ...

   Flash,Memory,Bottleneck,Limitation,Futur     2011-08-12 07:31:34

  How does Base64 work

Base64 is a data encoding scheme used in safe data transfer such as HTTP and its extensions. Base64 encoding can conver arbitrary group of bytes into a sequence of readable ASCII characters. These converted characters can safely put in a HTTP header without causing any problem while the peers process the HTTP header. Base64 encoding was invented as part of the MIME content transfer encoding. It is similar to other encoding schemes such as Uuencode and BinHex but with higher efficiency....

   ALGORITHM,BASE64     2016-03-09 23:47:40

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