View Category
Numbers
Mathematical

Find the distance between two points

ruby
# the hypotenuse sqrt(x**2+y**2)
distance = Math.hypot(x2-x1,y2-y1)
erlang
Distance = distance({point, 34, 78}, {point, 67, -45}),
io:format("~.2f~n", [Distance]).
Distance = distance(point:new(34, 78), point:new(67, -45)),
io:format("~.2f~n", [Distance]).
csharp
System.Drawing.Point p = new System.Drawing.Point(13, 14),
p1 = new System.Drawing.Point(10, 10);
double distance = Math.Sqrt(Math.Pow(p1.X - p.X, 2) + Math.Pow(p1.Y - p.Y, 2)));
fsharp
let distance' = distance (34, 78) (67, -45)
printfn "%3.2f" distance'
fantom
px1 := 34.0f; py1 := 78.0f; px2 := 67.0f; py2 := -45.0f
distance := |Float x1, Float y1, Float x2, Float y2 -> Float|
{ ((x2-x1).pow(2.0f) + (y2-y1).pow(2.0f)).sqrt }

distance(px1, py1, px2, py2)
Output

Zero pad a number

Given the number 42, pad it to 8 characters like 00000042
ruby
42.to_s.rjust(8,"0")
"%08d" % 42
erlang
Formatted = io_lib:format("~8..0B", [42]),
io:format("~8..0B~n", [42]).
csharp
string.Format("{0,8:D8}", 42);
fsharp
printfn "%08d" 42
let formatted = sprintf "%08d" 42
printfn "%s" formatted
let buffer = new StringBuilder()
Printf.bprintf buffer "%08d" 42
printfn "%s" (buffer.ToString())
let formatted = String.Format("{0,8:D8}", 42)
Console.WriteLine(formatted)
let formatted = Convert.ToString(42).PadLeft(8, '0')
Console.WriteLine(formatted)
fantom
formatted := 42.toStr.padl(8, '0')
formatted := 42.toLocale("00000000")

Right Space pad a number

Given the number 1024 right pad it to 6 characters "1024  "
ruby
1024.to_s.ljust(6)
erlang
Formatted = io_lib:format("~-6B", [1024]),
io:format("~-6B~n", [1024]).
csharp
public class NumberRightPadding {
public static void Main() {
string withStringDotFormat = string.Format("{0,-6}", 1024);
string withToStringDotPadRight = 1024.ToString().PadRight(6);
}
}
fsharp
printfn "%-6d" 1024
let formatted = String.Format("{0,-6:D}", 1024)
Console.WriteLine(formatted)
let formatted = Convert.ToString(1024).PadRight(6)
Console.WriteLine(formatted)
fantom
formatted := 1024.toStr.padr(6)

Format a decimal number

Format the number 7/8 as a decimal with 2 places: 0.88
ruby
(7.0/8.0*100).round/100.0
(7.0/8.0).round(2)
erlang
Formatted = io_lib:format("~.2f", [7/8]),
io:format("~.2f~n", [7/8]).
csharp
public class FormatDecimal {
public static void Main() {
decimal result = decimal.Round( 7 / 8m, 2);
System.Console.WriteLine(result);
}
}
fsharp
printfn "%3.2f" (0.7 / 0.8)
let formatted = String.Format("{0,3:F2}", (0.7 / 0.8))
Console.WriteLine(formatted)
fantom
formatted := (7.0/8.0).toLocale("0.00")

Left Space pad a number

Given the number 73 left pad it to 10 characters "        73"
ruby
73.to_s.rjust(10)
erlang
Formatted = io_lib:format("~10B", [73]),
io:format("~10B~n", [73]).
csharp
public class NumberLeftPadding {
public static void Main() {
string withStringDotFormat = string.Format("{0,10}", 73);
string withToStringDotPadLeft = 73.ToString().PadLeft(10);
}
}
fsharp
let formatted = sprintf "%10d" 73
printfn "%s" formatted
let formatted = String.Format("{0,10:D}", 73)
Console.WriteLine(formatted)
let formatted = Convert.ToString(73).PadLeft(10)
Console.WriteLine(formatted)
fantom
formatted := 73.toStr.padl(10)
Random

Generate a random integer in a given range

Produce a random integer between 100 and 200 inclusive
ruby
randomInt = rand(200-100+1)+100;
erlang
RandomInt = gen_rand_integer(100, 200),
csharp
System.Random r = new System.Random();
int random = r.Next(100,201);
fsharp
let rnd = new Random()
let rndInt = rnd.Next(100, 201)
fantom
r := Int.random(100..200)

Generate a repeatable random number sequence

Initialise a random number generator with a seed and generate five decimal values. Reset the seed and produce the same values.
ruby
srand(12345)
first = (1..5).collect {rand}
srand(12345)
second = (1..5).collect {rand}
puts first == second
erlang
setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]),

setRNG(RNGState),
io:format("~w~n", [lists:map(fun (_) -> gen_rand_integer(100, 200) end, lists:seq(1, 5))]).
csharp
using System;

public class RepeatableRandom {
public static void Main() {
var r = new Random(12); // seed is 12

for (int i = 0; i < 5; i++)
Console.WriteLine(r.Next());

r = new Random(12);

for (int i = 0; i < 5; i++)
Console.WriteLine(r.Next());
}
}

fsharp
let (seed, lb, ub) = (12345, 100, 200)

let mutable rnd = new Random(seed)
for i = 1 to 5 do printf "%d " (rnd.Next(lb, ub + 1)) done ; printfn ""

rnd <- new Random(seed)
for i = 1 to 5 do printf "%d " (rnd.Next(lb, ub + 1)) done ; printfn ""
fantom
rand := Random.makeSeeded(12345)
first := Int[,].fill(0,5).map { rand.next(100..200) }

rand2 := Random.makeSeeded(12345)
second := Int[,].fill(0,5).map { rand2.next(100..200) }