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I'm looking for a function that return me a mathematic function following those examples:
The_Function_I_Need("x^2") = function(x) { return math.pow(x, 2) }
The_Function_I_Need("x*2+5") = function(x) { return 2*x+5 }
The_Function_I_Need("x+y") = function(x, y) { return x+y }
And more..
var The_Function_I_Need = {
"x^2": function(x) {
return Math.pow(x, 2);
},
"x*2+5": function(x) {
return 2 * x + 5;
},
"x+y": function(x, y) {
return x + y;
}
}
console.log(The_Function_I_Need["x^2"](4))
console.log(The_Function_I_Need["x*2+5"](4))
console.log(The_Function_I_Need["x+y"](2, 4))
The Javascript eval() function can evaluate a string as an expression.
To follow your example, you could just use eval("x^2").
Reference: http://www.w3schools.com/jsref/jsref_eval.asp
Related
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I have code with if statement (below). Is it possible to refactor this code? because in this method is ugly if statement :(
getOverallAmount(estimate) {
const {installments} = estimate;
const {vipValue} = estimate;
if (installments !== 1) {
const oneInstallment = vipValue / installments;
const allWithOneInst = vipValue - (oneInstallment * installments) + 1;
return oneInstallment + allWithOneInst;
}
return vipValue;
}
Using a ternary operator instead of the if statement:
getOverallAmount(estimate) {
const {installments} = estimate;
const {vipValue} = estimate;
const oneInstallment = vipValue / installments;
const allWithOneInst = vipValue - (oneInstallment * installments) + 1;
return (installments !== 1) ? oneInstallment + allWithOneInst : vipValue;
}
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Say I have an array like so...
let myArr = [0,0,2,0,0];
I want to create sort of a ripple effect such that the result of the array is [0,1,2,1,0]
This would give you the result you expect:
let myArr = [0, 0, 2, 0, 0];
createRippleArray = (myArr) => {
if (myArr.length % 2 === 0) {
console.error("createRippleArray: Array length needs to be odd number>1");
return [];
}
let midIndex = ~~(myArr.length / 2);
let mid = myArr[midIndex];
return myArr.map((e, i) => {
let res;
if (i < midIndex) {
return ~~(mid / Math.abs(midIndex - i + 1));
} else if (i === midIndex) {
return mid;
} else if (i > midIndex) {
return ~~(mid / Math.abs(midIndex - i - 1));
}
});
}
console.log(createRippleArray(myArr));
Hope this helps!
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I have the next code in javascript:
var exponential = 2.71828182845904523536028747135266249775724709369995957496696762772407663035354759457138217852516642742746;
var numerator, denominator;
function fact(x) {
if(x==0) {
return 1;
}
return x * fact(x-1);
}
function poisson(k, landa) {
exponentialPower = Math.pow(exponential, -landa); // negative power k
landaPowerK = Math.pow(landa, k); // Landa elevated k
numerator = exponentialPower * landaPowerK;
denominator = fact(k); // factorial of k.
return (numerator / denominator);
}
I need parse to php but i don't know how...
Can somebody help me?
you should put below variables within poisson function also dont think you need to initialize $numerator and $dominator to 0;
$exponential = 2;
$numerator = 0;
$dominator = 0;
function fact($x) {
if($x==0) {
return 1;
}
return $x * fact($x-1);
}
function poisson($k, $landa)
{
$exponential = 2;
$exponentialPower = pow($exponential, -$landa);
$landaPowerK = pow($landa,$k);
$numerator = $exponentialPower * $landaPowerK;
$dominator = fact($k);
echo ($numerator / $dominator);
}
poisson(1,2);
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var x = function (a) { return a + a/4 - 600}
I have a function that does something.
So now my goal is to repeat this function 12 times with an argument used from previous operation;
Let's say initial ammount is 5000;
So
`x(5000) = 5650;
x(5650) =6462.5;
x(6462.) =...;
and this should be repeated 12 times;
So how can this be done in code?
`
Certainly the easiest way would be to use a for loop:
var x = function(a) { return a + a/4 - 600 },
v = 5000;
for (var i = 0; i < 12; i++) {
v = x(v);
}
console.log(v);
I'd not recommend doing something like this, but instead of a loop you could use recursion:
var x = function(42.34, 12);
----
function(double a, int maxSize)
{
a = ((a + a) / (4 - 600));
if(maxSize>0){
maxSize--;
return function(a,maxSize);
}else{
return a;
}
}
(just pseudocode)
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Task: to write a function foo.
function arg1(a,b) {
return a + b;
}
var x = foo(arg1, arg2);
x(arg3); // return arg2 + arg3
var y = foo(arg1, arg2, arg3);
y(); // return arg2 + arg3
I can't understand how at first var x, y - numbers ( because arg1() return number ), and then x, y - functions. How is it possible?
What you want is higher order function curry, a function that will return another function
function add(a,b) {
return a + b;
}
function curry(fun) {
var args = [].slice.call(arguments);
args.shift();
return function() {
return fun.apply(null, args.concat([].slice(arguments)));
};
}
x = curry(add, 10, 20);
x();
if you want to add more then two arguments you need to rewrite add function, you can iterate or use another higher order function reduce.
function add() {
[].slice.call(null, arguments).reduce(function(a, b) { return a+b; });
}
Or you can use #PaulS. solution using reduce in your foo function to call it to more then one argument:
function foo(fun) {
var args = [].slice.call(arguments);
args.shift();
return function() {
return args.concat([].slice.call(arguments)).reduce(fun);
};
};
var x = foo(add, 10, 20, 30);
x(30);