It works for -3,-2,-1 but for 0 and 1 it’s infinite NaN so,what to do ?

import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc = new Scanner(System.in); double x; System.out.print("x="); x = sc.nextDouble(); sc.close(); System.out.println("result:"); if (x < -3 || x > 1) { System.out.println("error"); return; } double s, a; int i; s = (double)1/3; a = 1; i = 9; while(Math.abs(a/i)>0.0001) { a=-a((x+2)(x+2)); s=s+(a/i); System.out.println(s); i=i3; } System.out.printf("function=%.4f", 1/(((xx)+(4*x)+7))); System.out.printf("\nsumma=%.4f", s); } }