Problems with fractional powers (when I build function)

[MAGNETO903]

I have a simple expression log(x)^(1/3) (1) which is equivalent cbrt(log(x)) (2)

I built expression (1) var f = nerdamer("log(x)^(1/3)").buildFunction() and then tried to use it

console.log(f(0)) // Infinity
console.log(f(0.2)) // NaN
console.log(f(0.99)) // NaN

it fails

But when I build expression (2) var f2 = nerdmamer("cbrt(log(x))").buildFunction() and tested

console.log(f2(0)) // -Infinity
console.log(f2(0.2)) // -1.17190230687955
console.log(f2(0.99)) // -0.2158043485359359

that's right

[MAGNETO903]

Thats occurs, because Math.pow(n, x) cant calculate when n<0 and x<1.

var f = nerdamer("log(x)^(1/3)").buildFunction();
console.log(f.toString()) 
// function anonymous(x
//) {
// return Math.pow(Math.log(x),0.3333333333333333333333333333333333333333333333333333333333333333333333333333333);
//}

So, I can write my own nthRoot(n, x) and say nerdamer to use nthRoot(n, x) instead of Math.pow()

[jiggzson]

@MAGNETO903. yes you can. You can define your own function name nthRoot function but make sure you also define it's numeric equivalent within the Math2 object. I'll try to provide an example soon.

[jiggzson]

@MAGNETO903, was your issue resolved?

[MAGNETO903]

@jiggzson, no, Unfortunatly

[jiggzson]

@MAGNETO903, here's an interesting observation. You get the same issue when using Wolfram Alpha.

Here's log(x)^(1/3) and here's cbrt(log(x)). Wolfram Alpha gives a complex value for one and not the other.