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Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
...a list of many others) is that it tends to artificially favor lookup table based solutions. Since the benchmark is repeating the one operation in a loop, it will often find that using a lookup table that just fits in L1 is the fastest, because everything will hit in L1 every time since there is no c...
How to smooth a curve in the right way?
...
A quick and dirty way to smooth data I use, based on a moving average box (by convolution):
x = np.linspace(0,2*np.pi,100)
y = np.sin(x) + np.random.random(100) * 0.8
def smooth(y, box_pts):
box = np.ones(box_pts)/box_pts
y_smooth = np.convolve(y, box, mode='...
How do I achieve the theoretical maximum of 4 FLOPs per cycle?
...sh:~ mackie$ clang -v
Apple clang version 3.0 (tags/Apple/clang-211.10.1) (based on LLVM 3.0svn)
Target: x86_64-apple-darwin11.2.0
Thread model: posix
The inner loop of clang's code looks like this:
.align 4, 0x90
LBB2_4: ## =>This Inner Loop Header: De...
What does the * * CSS selector do?
... for help, clarification, or responding to other answers.Making statements based on opinion; back them up with references or personal experience.To learn more, see our tips on writing great answers.
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PostgreSQL create table if not exists
... */ sch.foo (
id serial NOT NULL,
demo_column varchar NOT NULL,
demo_column2 varchar NOT NULL,
CONSTRAINT pk_sch_foo PRIMARY KEY (id));
CREATE INDEX /* IF NOT EXISTS add for PostgreSQL 9.5+ */ idx_sc...
How do I decode HTML entities in Swift?
...("20ac", 16) --> "€"
func decodeNumeric(_ string : Substring, base : Int) -> Character? {
guard let code = UInt32(string, radix: base),
let uniScalar = UnicodeScalar(code) else { return nil }
return Character(uniScalar)
}
// De...
Case insensitive searching in Oracle
... force a full table scan. In order to avoid this you can create a function-based index.
create index my_index on my_table ( lower(column_1) );
If you're using LIKE then you have to concatenate a % around the string you're searching for.
select * from my_table where lower(column_1) LIKE lower('my...
怎么通过app inventor接收mqtt平台推送的长消息 - App Inventor 2 中文网 -...
我使用的MQTT平台是mind+的siot平台，发布的消息是图片的BASE64编码
你好，mqtt接收长消息目前是有什么问题吗？请提供详细的问题截图或报错信息。
接收的base64编码的图片，可以是使用拓展解码还原成图片：https://www.fun123.cn/ref...
Make footer stick to bottom of page correctly [duplicate]
... <html> tag and position the <footer> with position:absolute;
Demo: jsfiddle and SO snippet:
html {
position: relative;
min-height: 100%;
}
body {
margin: 0 0 100px;
/* bottom = footer height */
padding: 25px;
}
footer {
background-color: orang...
rgdal package installation
...ibgdal1-dev libproj-dev
One tip that can be useful, still under a Debian based system, is to install the apt-file package and run :
$ sudo apt-file update
Then, when you get an error such as :
configure: error: proj_api.h not found in standard or given locations.
You can use the following co...