Allow for powers of big exponents

[alatcache]

I needed to get the power of some big numbers and found the limitations of .pow() a bit restricting. This alternative version takes advantage of the fact that given x, where 10^x = a^b, we can say x = b * log(10)a.

Anyway, thought this might help someone or lead to an enhanced .pow() function. Thanks for this great resource.

function big_pow(number,exponent) {
var nu = new Big(number);
var ex = new Big(exponent);
var ten = new Big('10');

// If the exponent is small use .pow()
if (ex.e < 3) return nu.pow(parseFloat(ex.toString()));

// Create a Big for the result
var res = new Big('1');

// Get coefficient as number
var coef_nu = parseFloat(nu.c[0] + '.' + nu.c.slice(1).join(''));

// Get coefficient's log10 value
var log_nu = Big((Math.log(coef_nu) / Math.LN10) + parseFloat(nu.e));

// Multiply by the exponent supplied
var res_exp = log_nu.times(ex);

// Get non-integer portion
var res_rem = res_exp.minus(res_exp.round(0, 0));
var f_res_rem = parseFloat(res_rem.toString());

// To the power 10 gives us the result coefficient
var res_comp = new Big(Math.pow(10,f_res_rem));

// Stuff values into the result
res.e = res_exp.round(0, 0);
res.c = res_comp.c;
return res;
}

I've done a bit of checking - but definitely supplied 'as is' ...

[whatgoodisaroad]

What a great contribution! I'll definitely plan on working this in. Thanks!