Method log

__test__/theorem.js:102–107

(x, base, n = 15)

      return new BigNumber(Number(.5*Math.log(2*Math.PI)+(z+.5)*Math.log(t)-t+Math.log(x)-Math.log(z)).toFixed(10));
  }
  log(x, base, n = 15) {
  	if (x.isComplex) {
  		return x.log(base)
  	}
  	return new BigNumber(this.ln(x, n).div(this.ln(base, n)).toFixed(n - 1))
  }
  pow(n, base) {
      if (typeof n != 'object' || BigNumber.isBigNumber(n)) {
          n = [n]