derivative in js

derivative.js

function derivative(f) {
   var h = 0.001;
   return function(x) { return (f(x + h) - f(x - h)) / (2 * h); };
}
 
console.log(" cos(2) = " + Math.cos(2));
console.log("-sin(2) = " + Math.sin(2));
console.log("(d cos/dx)(2) = " + derivative(Math.cos)(2));
 
function f(x) { return Math.pow(x, 3) + 2 * x + 1; };
var x = 12.5;
 
console.log("[6x | x = 12.5] = " + (6 * x);
console.log("(d^2 (x^3 + 2x + 1)/dx^2)(12.5) = " + 
    derivative(derivative(f))(x));

This is very short and gives approimately accurate value. Even no teacher in the school tells you what 'h' really is. This short piece of code has inspired me to bring more 'maths' to my JS code. Thanks!

https://repl.it/IuxU

👍