console.log(Math.tanh(-1));
// expected output: -0.7615941559557649

console.log(Math.tanh(0));
// expected output: 0

console.log(Math.tanh(Infinity));
// expected output: 1

console.log(Math.tanh(1));
// expected output: 0.7615941559557649

Math.tanh(0);        // 0
Math.tanh(Infinity); // 1
Math.tanh(1);        // 0.7615941559557649

Dot Product Matrix in Go

by yhuang Go mat.NewDense fmt fmt.Printf gonum.org/v1/gonum/mat mat.Dense

package main

import (
	"fmt"

	"gonum.org/v1/gonum/mat"
)

func main() {

	// Initialize two matrices, a and b.
	a := mat.NewDense(2, 2, []float64{
		4, 0,
		0, 4,
	})
	b := mat.NewDense(2, 3, []float64{
		4, 0, 0,
		0, 0, 4,
	})

	// Take the matrix product of a and b and place the result in c.
	var c mat.Dense
	c.Mul(a, b)

	// Print the result using the formatter.
	fc := mat.Formatted(&c, mat.Prefix("    "), mat.Squeeze())
	fmt.Printf("c = %v", fc)
}

Last Run  :
c = ⎡16  0   0⎤
    ⎣ 0  0  16⎦

Get Num Leading Zeros (32bit int) in JavaScript

by yhuang JavaScript

// 00000000000000000000000000000001
console.log(Math.clz32(1));
// expected output: 31

// 00000000000000000000000000000100
console.log(Math.clz32(4));
// expected output: 29

// 00000000000000000000001111101000
console.log(Math.clz32(1000));
// expected output: 22

Math.clz32(1);           // 31
Math.clz32(1000);        // 22
Math.clz32();            // 32

var stuff = [NaN, Infinity, -Infinity, 0, -0, null, undefined, 'foo', {}, []];
stuff.every(n => Math.clz32(n) == 32);  // true

Math.clz32(true);        // 31
Math.clz32(3.5);         // 30

Generate Random Numbers in JavaScript

by yhuang JavaScript

function getRandomInt(max) {
  return Math.floor(Math.random() * Math.floor(max));
}

console.log(getRandomInt(3));
// expected output: 0, 1 or 2

console.log(getRandomInt(1));
// expected output: 0

console.log(Math.random());
// expected output: a number between 0 and 1

function getRandomArbitrary(min, max) {
  return Math.random() * (max - min) + min;
}

Compute Absolute Number in JavaScript

by yhuang JavaScript

function difference(a, b) {
  return Math.abs(a - b);
}

console.log(difference(3, 5));
// expected output: 2

console.log(difference(5, 3));
// expected output: 2

console.log(difference(1.23456, 7.89012));
// expected output: 6.6555599999999995

Math.abs('-1');     // 1
Math.abs(-2);       // 2
Math.abs(null);     // 0
Math.abs('');       // 0
Math.abs([]);       // 0
Math.abs([2]);      // 2
Math.abs([1,2]);    // NaN
Math.abs({});       // NaN
Math.abs('string'); // NaN
Math.abs();         // NaN

Compute Ceiling in JavaScript

by yhuang JavaScript

Computes the least integer value greater than or equal to x.

console.log(Math.ceil(.95));
// expected output: 1

console.log(Math.ceil(4));
// expected output: 4

console.log(Math.ceil(7.004));
// expected output: 8

console.log(Math.ceil(-7.004));
// expected output: -7

Math.ceil(.95);    // 1
Math.ceil(4);      // 4
Math.ceil(7.004);  // 8
Math.ceil(-0.95);  // -0
Math.ceil(-4);     // -4
Math.ceil(-7.004); // -7

Compute Floor in JavaScript

by yhuang JavaScript

Compute the greatest integer value less than or equal to x.

console.log(Math.floor(5.95));
// expected output: 5

console.log(Math.floor(5.05));
// expected output: 5

console.log(Math.floor(5));
// expected output: 5

console.log(Math.floor(-5.05));
// expected output: -6

Math.floor( 45.95); //  45
Math.floor( 45.05); //  45
Math.floor(  4   ); //   4
Math.floor(-45.05); // -46 
Math.floor(-45.95); // -46

Round Number in JavaScript

by yhuang JavaScript

Round returns the nearest integer, rounding half away from zero.

console.log(Math.round(0.9));
// expected output: 1

console.log(Math.round(5.95), Math.round(5.5), Math.round(5.05));
// expected output: 6 6 5

console.log(Math.round(-5.05), Math.round(-5.5), Math.round(-5.95));
// expected output: -5 -5 -6

Math.round( 20.49); //  20
Math.round( 20.5 ); //  21
Math.round( 42   ); //  42
Math.round(-20.5 ); // -20
Math.round(-20.51); // -21

Compute Max in JavaScript

by yhuang JavaScript

console.log(Math.max(1, 3, 2));
// expected output: 3

console.log(Math.max(-1, -3, -2));
// expected output: -1

var array1 = [1, 3, 2];

console.log(Math.max(...array1));
// expected output: 3

Math.max(10, 20);   //  20
Math.max(-10, -20); // -10
Math.max(-10, 20);  //  20

Compute Min in JavaScript

by yhuang JavaScript

console.log(Math.min(2, 3, 1));
// expected output: 1

console.log(Math.min(-2, -3, -1));
// expected output: -3

var array1 = [2, 3, 1];

console.log(Math.min(...array1));
// expected output: 1

Compute Modulus in Go

by yhuang Go fmt fmt.Printf math math.Mod

Computes the remainder after division of one number by another.

package main

import (
	"fmt"
	"math"
)

func main() {
	c := math.Mod(7, 4)
	fmt.Printf("%.1f", c)
}

Compute Square Root in JavaScript

by yhuang JavaScript

function calcHypotenuse(a, b) {
  return(Math.sqrt((a * a) + (b * b)));
}

console.log(calcHypotenuse(3, 4));
// expected output: 5

console.log(calcHypotenuse(5, 12));
// expected output: 13

console.log(calcHypotenuse(0, 0));
// expected output: 0

Math.sqrt(9); // 3
Math.sqrt(2); // 1.414213562373095

Math.sqrt(1);  // 1
Math.sqrt(0);  // 0
Math.sqrt(-1); // NaN
Math.sqrt(-0); // -0

Compute Cube Root in Go

by yhuang Go fmt fmt.Println math math.Cbrt

package main

import (
    "fmt"
    "math"
)

func main() {
  fmt.Println(math.Cbrt(27))
}

Compute Natural Exponential in JavaScript

by yhuang JavaScript

console.log(Math.exp(0));
// expected output: 1

console.log(Math.exp(1));
// expected output: 2.718281828459 (approximately)

console.log(Math.exp(-1));
// expected output: 0.36787944117144233

console.log(Math.exp(2));
// expected output: 7.38905609893065

Math.exp(-1); // 0.36787944117144233
Math.exp(0);  // 1
Math.exp(1);  // 2.718281828459045

Compute Natural Exponential - 1 in JavaScript

by yhuang JavaScript

Computes an implementation-dependent approximation to subtracting 1 from the exponential function of x (e raised to the power of x, where e is the base of the natural logarithms). The result is computed in a way that is accurate even when the value of x is close 0.

console.log(Math.expm1(0));
// expected output: 0

console.log(Math.expm1(1));
// expected output: 1.718281828459045

console.log(Math.expm1(-1));
// expected output: -0.6321205588285577

console.log(Math.expm1(2));
// expected output: 6.38905609893065

Math.expm1(-1); // -0.6321205588285577 
Math.expm1(0);  // 0
Math.expm1(1);  // 1.718281828459045

Compute Base2 Exponential in Go

by yhuang Go fmt fmt.Printf math math.Exp2

package main

import (
	"fmt"
	"math"
)

func main() {
	fmt.Printf("%.2f", math.Exp2(10))
}

Compute any-Base Exponential in JavaScript

by yhuang JavaScript

console.log(Math.pow(7, 3));
// expected output: 343

console.log(Math.pow(4, 0.5));
// expected output: 2

console.log(Math.pow(7, -2));
// expected output: 0.02040816326530612
//                  (1/49)

console.log(Math.pow(-7, 0.5));
// expected output: NaN

// simple
Math.pow(7, 2);    // 49
Math.pow(7, 3);    // 343
Math.pow(2, 10);   // 1024
// fractional exponents
Math.pow(4, 0.5);  // 2 (square root of 4)
Math.pow(8, 1/3);  // 2 (cube root of 8)
Math.pow(2, 0.5);  // 1.4142135623730951 (square root of 2)
Math.pow(2, 1/3);  // 1.2599210498948732 (cube root of 2)
// signed exponents
Math.pow(7, -2);   // 0.02040816326530612 (1/49)
Math.pow(8, -1/3); // 0.5
// signed bases
Math.pow(-7, 2);   // 49 (squares are positive)
Math.pow(-7, 3);   // -343 (cubes can be negative)
Math.pow(-7, 0.5); // NaN (negative numbers don't have a real square root)
// due to "even" and "odd" roots laying close to each other, 
// and limits in the floating number precision, 
// negative bases with fractional exponents always return NaN
Math.pow(-7, 1/3); // NaN

Compute Natural Logarithm in JavaScript

by yhuang JavaScript

Math.log(-1); // NaN, out of range
Math.log(0);  // -Infinity
Math.log(1);  // 0
Math.log(10); // 2.302585092994046

Compute Natural Logarithm x + 1 in JavaScript

by yhuang JavaScript

Compute an implementation-dependent approximation to the natural logarithm of 1 + x. The result is computed in a way that is accurate even when the value of x is close to zero.

console.log(Math.log1p(1));
// expected output: 0.6931471805599453

console.log(Math.log1p(0));
// expected output: 0

console.log(Math.log1p(-1));
// expected output: -Infinity

console.log(Math.log1p(-2));
// expected output: NaN

Math.log1p(1);  // 0.6931471805599453
Math.log1p(0);  // 0
Math.log1p(-1); // -Infinity
Math.log1p(-2); // NaN

Compute Binary Logarithm in JavaScript

by yhuang JavaScript

console.log(Math.log2(3));
// expected output: 1.584962500721156

console.log(Math.log2(2));
// expected output: 1

console.log(Math.log2(1));
// expected output: 0

console.log(Math.log2(0));
// expected output: -Infinity

Math.log2(3);    // 1.584962500721156
Math.log2(2);    // 1
Math.log2(1);    // 0
Math.log2(0);    // -Infinity
Math.log2(-2);   // NaN
Math.log2(1024); // 10

Compute Decimal Logarithm in JavaScript

by yhuang JavaScript

console.log(Math.log10(100000));
// expected output: 5

console.log(Math.log10(2));
// expected output: 0.3010299956639812

console.log(Math.log10(1));
// expected output: 0

console.log(Math.log10(0));
// expected output: -Infinity

Math.log10(2);      // 0.3010299956639812
Math.log10(1);      // 0
Math.log10(0);      // -Infinity
Math.log10(-2);     // NaN
Math.log10(100000); // 5

Compute any-Base Logarithm in Go

by yhuang Go math.Log fmt fmt.Printf math

package main

import (
	"fmt"
	"math"
)

func LogAny(x, b float64) float64 {
  return math.Log(x) / math.Log(b)
}

func main() {
  fmt.Printf("%.1f", LogAny(27, 3))
}

Last Run  :
3.0

Compute Root of Sum of Squares in JavaScript

by yhuang JavaScript

Computes the square root of the sum of squares of its arguments, that is:

console.log(Math.hypot(3, 4));
// expected output: 5

console.log(Math.hypot(5, 12));
// expected output: 13

console.log(Math.hypot(3, 4, 5));
// expected output: 7.0710678118654755

console.log(Math.hypot(-5));
// expected output: 5

Math.hypot(3, 4);        // 5
Math.hypot(3, 4, 5);     // 7.0710678118654755
Math.hypot();            // 0
Math.hypot(NaN);         // NaN
Math.hypot(3, 4, 'foo'); // NaN, +'foo' => NaN
Math.hypot(3, 4, '5');   // 7.0710678118654755, +'5' => 5
Math.hypot(-3);          // 3, the same as Math.abs(-3)

Compute Error Function in Go

by yhuang Go fmt fmt.Printf math math.Erf

package main

import (
	"fmt"
	"math"
)

func main() {
	c := math.Erf(1.0)
	fmt.Printf("%.6f", c)
}

Compute Complementary Error Function in Go

by yhuang Go fmt fmt.Printf math math.Erfc

package main

import (
	"fmt"
	"math"
)

func main() {
	c := math.Erfc(1.0)
	fmt.Printf("%.6f", c)
}

Compute Inverse Complementary Error in Go

by yhuang Go fmt fmt.Printf math math.Erfcinv

package main

import (
	"fmt"
	"math"
)

func main() {
	c := math.Erfcinv(1.5)
	fmt.Printf("%.6f", c)
}

Compute Inverse Error in Go

by yhuang Go fmt fmt.Printf math math.Erfinv

package main

import (
	"fmt"
	"math"
)

func main() {
	c := math.Erfinv(0.5)
	fmt.Printf("%.6f", c)
}

Compute Gamma Function in Go

by yhuang Go fmt fmt.Printf math math.Gamma

package main

import (
	"fmt"
	"math"
)

func main() {
	c := math.Gamma(10.0)
	fmt.Printf("%.1f", c)
}

Get Not a Number in Go

by yhuang Go fmt fmt.Println math math.NaN

package main

import (
  "fmt"
  "math"
)

func main() {
  not_a_number := math.NaN()
  fmt.Println(not_a_number)
}

Compute Sign in JavaScript

by yhuang JavaScript

Computes either a positive or negative 1, indicating the sign of a number passed into the argument. If the number argument is 0, it will return 0.

console.log(Math.sign(3));
// expected output: 1

console.log(Math.sign(-3));
// expected output: -1

console.log(Math.sign(0));
// expected output: 0

console.log(Math.sign('-3'));
// expected output: -1

Math.sign(3);     //  1
Math.sign(-3);    // -1
Math.sign('-3');  // -1
Math.sign(0);     //  0
Math.sign(-0);    // -0
Math.sign(NaN);   // NaN
Math.sign('foo'); // NaN
Math.sign();      // NaN

Is Not a Number in Go

by yhuang Go fmt fmt.Println math math.IsNaN math.Log

Returns whether float x is an IEEE 754 “not-a-number” value.

package main

import (
  "fmt"
  "math"
)

func main() {
  fmt.Println(math.IsNaN(math.Log(-1.0)))
}

Is Positive Infinity in Go

by yhuang Go fmt fmt.Println math math.Inf math.IsInf

package main

import (
  "fmt"
  "math"
)

func main() {
  posInf := math.Inf(1)
  fmt.Println(math.IsInf(posInf, 1))
}

Last Run  :
true

Is Negative Infinity in Go

by yhuang Go fmt fmt.Println math math.Inf math.IsInf

package main

import (
  "fmt"
  "math"
)

func main() {
  posInf := math.Inf(-1)
  fmt.Println(math.IsInf(posInf, -1))
}

Last Run  :
true

Compute Fibonacci in Ruby

by yhuang Ruby

def fibonacci( n )
  return  n  if ( 0..1 ).include? n
  ( fibonacci( n - 1 ) + fibonacci( n - 2 ) )
end
puts fibonacci( 5 )