CUMIPMT Function

CUMIPMT.js

// Copyright (c) 2012 Sutoiku, Inc. (MIT License)
 
// Some algorithms have been ported from Apache OpenOffice:
 
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function CUMIPMT(rate, periods, value, start, end, type) {
  // Credits: algorithm inspired by Apache OpenOffice
  // Credits: Hannes Stiebitzhofer for the translations of function and variable names
  // Requires getFutureValue() and getPartialPayment() from Formula.js [http://stoic.com/formula/]

  // Evaluate rate and periods (TODO: replace with secure expression evaluator)
  rate = eval(rate);
  periods = eval(periods);

  // Return error if either rate, periods, or value are lower than or equal to zero
  if (rate <= 0 || periods <= 0 || value <= 0) return '#NUM!';

  // Return error if start < 1, end < 1, or start > end
  if (start < 1 || end < 1 || start > end) return '#NUM!';

  // Return error if type is neither 0 nor 1
  if (type !== 0 && type !== 1) return '#NUM!';

  // Compute cumulative interest
  var payment = getPartialPayment(rate, periods, value, 0, type);
  var interest = 0;
  interest = 0;
  if(start === 1) {
    if(type === 0) {
      interest = -value;
      start++;
    }
  }
  for (var i = start; i <= end; i++) {
    if (type === 1) {
      interest += getFutureValue(rate, i - 2, payment, value, 1 ) - payment;
    } else {
      interest += getFutureValue(rate, i - 1, payment, value, 0 );
    }
  }
  interest *= rate;

  // Return cumulative interest
  return interest;
}

The CUMIPMT calculation mentioned here is wrong. I compared the calculation value with Google Sheet or Excel and it is showing smaller value than CUMIPMT value shown in Google Sheet. Can someone tell me why?

I Got This Type of Error Uncaught ReferenceError: getPartialPayment is not defined