Complex expressions are not working

[jaydeepbhayani]

I have an expression like this -> "(0.341 * 8000.0) / (1 - (1 + 0.341) ^ -84)"

Expected result - "109.71908469357446"
Actual result - "1.538906384258725e-36"

calculation should be done like below snippet

fun calculateMonthlyInstallment(loanAmount: Double, monthlyInterestRate: Double, numberOfMonths: Int): Double {
    val monthlyInterestRateDecimal = monthlyInterestRate / 100.0  // Convert percentage to decimal
    val power = Math.pow(1 + monthlyInterestRateDecimal, -numberOfMonths.toDouble())
    return (monthlyInterestRateDecimal * loanAmount) / (1 - power)
}

fun main() {
    val loanAmount = 8000.0
    val monthlyInterestRate = 0.341  // 0.5% interest rate
    val numberOfMonths = 84
    val monthlyInstallment = calculateMonthlyInstallment(loanAmount, monthlyInterestRate, numberOfMonths)
    println("Monthly Installment: $monthlyInstallment")
}

[murzagalin]

Hi, @jaydeepbhayani . Thanks for the feedback!

I think something is wrong with your calculations. I tested your expression and everything seems correct with the library.

I have an expression like this -> "(0.341 * 8000.0) / (1 - (1 + 0.341) ^ -84)"
Expected result - "109.71908469357446"

I tested the expected result with wolfram alpha: calculation link . Please check it, the expected result is 2728.0000000539295785612886912317598649469480731689161625146408794

and the result from the library is 2728.0000000539294

[murzagalin]

I also checked your code, and it does not match the expression provided.

I added a comment to the main function to highlight the mistake you made

fun main() {
    val loanAmount = 8000.0
    val monthlyInterestRate = 34.1 // THIS LINE: you convert this percentage value by dividing by 100 in the function later
    val numberOfMonths = 84
    val monthlyInstallment = calculateMonthlyInstallment(loanAmount, monthlyInterestRate, numberOfMonths)
    println("Monthly Installment: $monthlyInstallment")
}

[murzagalin]

I added the test case for this expression: test link