bigdecimal - Million elements of PI in Java BBP formula -


i try implement bbp formula calculating milion elements of pi. have problem calculating , displaying results. when set i 1 000 000 in loop , mathcontext() more 1000 program not ending. paste code below, please help.

import java.math.bigdecimal; import java.math.mathcontext; import java.math.roundingmode;  public class rsi {     public static void main(string[] args) {         bigdecimal iterationresult, temp, temp2, temp3, temp4, temp5,              one, two, four, five, six, eight, sixteen, ii, result, pd, tc;         result = new bigdecimal(0);         result.setscale(1000000, roundingmode.half_down);          (int = 0; < 1000000; i++) {             pd = new bigdecimal(0);             tc = new bigdecimal(0);              temp = new bigdecimal(0);             temp2 = new bigdecimal(0);             temp3 = new bigdecimal(0);             temp4 = new bigdecimal(0);             temp5 = new bigdecimal(0);             2 = new bigdecimal(2);             4 = new bigdecimal(4);             5 = new bigdecimal(5);             6 = new bigdecimal(6);             8 = new bigdecimal(8);             sixteen = new bigdecimal(16);             1 = new bigdecimal(1);             iterationresult = new bigdecimal(0);             ii = new bigdecimal(i);              // calculate 1/16^i              temp = one.divide((sixteen.pow(i)), new mathcontext(10,                     roundingmode.half_down));              // calculate 4/(8*i+1) first word             temp2 = four.divide((eight.multiply(ii)).add(one), new mathcontext(                     1000, roundingmode.half_down));              // calculate 2/(8*i+4) second word             temp3 = two.divide((eight.multiply(ii)).add(four), new mathcontext(                     1000, roundingmode.half_down));              // calculate 1/(8*i+5) third word             temp4 = one.divide(((eight.multiply(ii)).add(five)),                     new mathcontext(1000, roundingmode.half_down));              // calculate 1/(8*i+6) fourth word             temp5 = one.divide(((eight.multiply(ii)).add(six)),                     new mathcontext(1000, roundingmode.half_down));              // calculate ( 4/(8*i+1) )-( 2/(8*i+4) ) first - second             pd = temp2.subtract(temp3);              // calculate -third-fourth word             tc = (temp4.negate()).subtract(temp5);              // calculate 1/16^k * ((first - second) + (-third - fourth))             iterationresult = temp.multiply((pd.add(tc)));              result = result.add(iterationresult);          }         system.out.println("result " + result);     } }

why can't display 1 million of digits when set loop 1 million , mathcontext million too?

the problem computer slow compute it. difficulty of task grows (probably n^3), if takes around 1 second compute 1 000 digits, take billion seconds compute 1 000 000 digits. apparently such tasks computed using heavily optimized code , using computational clusters. guess, bbp formula work better if use specially crafted data type performs intermediate computations in hexadecimal , convert decimal @ end print result. way 1/16^i step trivial. bigdecimal java type not optimal such computations.


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