excel的IRR函数

office官网找到IRR的介绍

https://support.office.com/zh-cn/article/irr-%E5%87%BD%E6%95%B0-64925eaa-9988-495b-b290-3ad0c163c1bc

https://docs.microsoft.com/zh-cn/office/vba/language/reference/user-interface-help/irr-function?f1url=https%3A%2F%2Fmsdn.microsoft.com%2Fquery%2Fdev11.query%3FappId%3DDev11IDEF1%26l%3Dzh-CN%26k%3Dk(vblr6.chm1009282)%3Bk(TargetFrameworkMoniker-Office.Version%3Dv15)%26rd%3Dtrue

1.找js的实现

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;  
}  

2. var一个 [] 来验证找到的函数 是否可用

3.调用IRR，estimatedResult设置为0.1，保持与excel默认值一致