Tutorial by Examples: n

This example uses the map format introduced in Erlang/OTP 18.0. %% A module implementing a supervisor usually has a name ending with `_sup`. -module(my_sup). -behaviour(supervisor). %% API exports -export([start_link/0]). %% Behaviour exports -export([init/1]). start_link() -> ...

We initialize the data: [X,Y] = meshgrid(1:2:10); Z = X.*cos(Y) - Y.*sin(X); The surface looks like the following. Now we set the points where we want to interpolate: [Vx,Vy] = meshgrid(1:0.25:10); We now can perform nearest interpolation, Vz = interp2(X,Y,Z,Vx,Vy,'nearest'); line...

We will use the following data: x = 1:5:50; y = randi([-10 10],1,10); Hereby x and y are the coordinates of the data points and z are the points we need information about. z = 0:0.25:50; One way to find the y-values of z is piecewise linear interpolation. z_y = interp1(x,y,z,'linear'); ...

To execute Javascript in python, use execute_script("javascript script here"). execute_script is called on a webdriver instance, and can be any valid javascript. from selenium import webdriver driver = webdriver.Chrome() driver.execute_script("alert('running javascript');") ...

Use conditional compilation to ensure that code only compiles for the intended instruction set (such as x86). Otherwise code could become invalid if the program is compiled for another architecture, such as ARM processors. #![feature(asm)] // Any valid x86 code is valid for x86_64 as well. Be ca...

#![feature(asm)] #[cfg(any(target_arch="x86", target_arch="x86_64"))] fn subtract(first: i32, second: i32) { unsafe { // Output values must either be unassigned (let result;) or mutable. let result: i32; // Each value that you pass in will b...

One implementation of the io.Reader interface can be found in the bytes package. It allows a byte slice to be used as the source for a Reader. In this example the byte slice is taken from a string, but is more likely to have been read from a file or network connection. message := []byte("Hello...

Send a Razor part to a @helper, for example a HTML div. @helper WrapInBox(Func<Object, HelperResult> content) { <div class="box">@content(null) </div> } //call @WrapInBox(@<div> I'm a inner div </div>)

Sometimes it may be required to find out which directory consuming how much disk space especially when you are used df -h and realized your available disk space is low. du: du command summarizes disk usage of the set of FILEs, recursively for directories. It's often uses with -sh option: -s, --s...

First, ensure you have installed mongodb and express via npm. Then, in a file conventionally titled db.js, use the following code: var MongoClient = require('mongodb').MongoClient var state = { db: null, } exports.connect = function(url, done) { if (state.db) return done() M...

The following example is high level coverage of the key concepts and basic skeletal setup:- Collects credentials from the user (Usually from a login screen you've created) Authenticates the credentials with the server (stores custom authentication) Stores the credentials on the device Exte...

A frequent reason why your read operation may not work is because your security rules reject the operation, for example because you're not authenticated (by default a database can only be accessed by an authenticated user). You can see these security rule violations in the JavaScript console of you...

Add a -behaviour directive to your module to indicate that it follows a behaviour: -behaviour(gen_server). The American spelling is also accepted: -behavior(gen_server). Now the compiler will give a warning if you've forgotten to implement and export any of the functions required by the beha...

You can define your own behaviour by adding -callback directives in your module. For example, if modules implementing your behaviour need to have a foo function that takes an integer and returns an atom: -module(my_behaviour). -callback foo(integer()) -> atom(). If you use this behaviour in...

It's easiest to show a binary search on numbers using pseudo-code int array[1000] = { sorted list of numbers }; int N = 100; // number of entries in search space; int high, low, mid; // our temporaries int x; // value to search for low = 0; high = N -1; while(low < high) { mid = (...

In this iText 5 example, we'll create a text field and we'll add it to a PDF: public void manipulatePdf(String src, String dest) throws DocumentException, IOException { PdfReader reader = new PdfReader(src); PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest)); T...

In this iText 7 example, we'll create a text field and we'll add it to a PDF: public void manipulatePdf(String src, String dest) throws IOException { PdfReader reader = new PdfReader(src); PdfDocument pdf = new PdfDocument(reader, new PdfWriter(dest)); PdfAcroForm form = PdfAcroFor...

In this iText 5 example, we'll change the properties and the value of a text field: public void manipulatePdf(String src, String dest) throws DocumentException, IOException { PdfReader reader = new PdfReader(src); PdfStamper stamper = new PdfStamper(reader, new FileOutputStream(dest)); ...

In this iText 7 example, we'll change the properties and the value of a text field: public void manipulatePdf(String src, String dest) throws IOException { PdfReader reader = new PdfReader(src); PdfDocument pdf = new PdfDocument(reader, new PdfWriter(dest)); PdfAcroForm form = PdfA...

Integer Basics Standard ML of New Jersey v110.78 [built: Thu Jul 23 11:21:58 2015] - 6; val it = 6 : int - ~6; val it = ~6 : int - 6 + ~6; val it = 0 : int Integer Division - 6 div 3; val it = 2 : int - 6 div 4; val it = 0 : int - 3 div 6; val it = 0 : int Integer Value Bounds Us...