function IRR(cashFlows, estimatedResult) {

  var result = "isNAN";

  if (cashFlows != null && cashFlows.length > 0) {

      // check if business startup costs is not zero:

      if (cashFlows[0] != 0) {

          var noOfCashFlows = cashFlows.length;

          var sumCashFlows = 0;

          // check if at least 1 positive and 1 negative cash flow exists:

          var noOfNegativeCashFlows = 0;

          var noOfPositiveCashFlows = 0;

          for (var i = 0; i < noOfCashFlows; i++) {

              sumCashFlows += cashFlows[i];

              if (cashFlows[i] > 0) {

                  noOfPositiveCashFlows++;

              } else {

                  if (cashFlows[i] < 0) {

                      noOfNegativeCashFlows++;

                  }

              }

          }  

          // at least 1 negative and 1 positive cash flow available?

          if (noOfNegativeCashFlows > 0 && noOfPositiveCashFlows > 0) {

              // set estimated result:

              var irrGuess = 0.1; // default: 10%

              if (!isNaN(estimatedResult)) {

                  irrGuess = estimatedResult;

                  if (irrGuess <= 0) {

                      irrGuess = 0.5;

                  }

              }  

              // initialize first IRR with estimated result:

              var irr = 0;

              if (sumCashFlows < 0) { // sum of cash flows negative?

                  irr = -irrGuess;

              } else { // sum of cash flows not negative

                  irr = irrGuess;

              }  

              // iteration:

              // the smaller the distance, the smaller the interpolation

              // error

              var minDistance = 1e-15;  

              // business startup costs

              var cashFlowStart = cashFlows[0];

              var maxIteration = 100;

              var wasHi = false;

              var cashValue = 0;

              for (var i = 0; i <= maxIteration; i++) {

                  // calculate cash value with current irr:

                  cashValue = cashFlowStart; // init with startup costs  

                  // for each cash flow

                  for (var j = 1; j < noOfCashFlows; j++) {

                      cashValue += cashFlows[j] / Math.pow(1 + irr, j);

                  }  

                  // cash value is nearly zero

                  if (Math.abs(cashValue) < 0.01) {

                      result = irr;

                      break;

                  }  

                  // adjust irr for next iteration:

                  // cash value > 0 => next irr > current irr

                  if (cashValue > 0) {

                      if (wasHi) {

                          irrGuess /= 2;

                      }

                      irr += irrGuess;

                      if (wasHi) {

                          irrGuess -= minDistance;

                          wasHi = false;

                      }

                  } else {// cash value < 0 => next irr < current irr

                      irrGuess /= 2;

                      irr -= irrGuess;

                      wasHi = true;

                  }  

                  // estimated result too small to continue => end

                  // calculation

                  if (irrGuess <= minDistance) {

                      result = irr;

                      break;

                  }

              }

          }

      }

  }

  return result;

}