financeFunctions/irr.js at master · maektwain/financeFunctions · GitHub

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    function IRR(loan,tenor,advanceEmi,flatRate){

  //set all the values 0 first

  //loan = 0;
  //tenor = 0;
  //emi = 0;
  //advanceEmi = 0;
  //flatRate = 0;

  //finding the interest first on the loan which has to be flat
  interest = loan * flatRate / 100 / 12 * tenor;
  //debug(interest);
  //finding the monthly emi

  emi = (interest + loan) / tenor ;
  //debug(emi)

  // intialising few loop variables

  I = 0;
  npv = null;

  // Deriving Outstanding Loan Amount

  loan_outstanding = loan - (advanceEmi * emi);
  //debug(loan_outstanding);

  //Deriving Tenor

  tenor = tenor - advanceEmi;
  //debug(tenor);

  //Documentation on IRR

  /*
  /*

  The below codes do the following
  first it needs to give the guessing range where it has to guess the IRR and then it has to loop through every period given

      */

  loan = loan -(advanceEmi * emi);
  for (irr = 1; irr < 100; irr = irr + 0.01){
    npv = 0.00;

    for (I = 1; I <= tenor; I++){
        //npv = npv + (emi /Math.pow(1+ irr/12,I));
        npv = npv + (emi/Math.pow((1+(irr/100/12)),I))

    //    debug(irr);
     //   debug(npv);
      //  debug(emi);
      //  debug(I);

    }
    if (npv <= loan){
      found = true;
      //debug(found);
      //debug(loan);
      //debug(npv);
      //break;
      return irr;
    }


    //debug("this is " + irr);
  }


}