Example: Interest Rate

Someone obtains a $20,000 loan to buy a car. They make $350 a month payments for 70 months. Here, the interest rate of the loan is computed. 
using System;
using Imsl.Finance;

public class rateEx1
{
    public static void  Main(String[] args)
    {
        int nper = 70;
        double pmt = - 350.0;
        double pv = 20000;
        double fv = 0.0;
        
        double rate = 12.0 * Finance.Rate(nper, pmt, pv, fv, 
                                          Finance.Period.AtBeginning);
        Console.Out.WriteLine("The computed interest rate on the loan " 
                              + "is " + rate.ToString("P"));
    }
}

Output

The computed interest rate on the loan is 7.35 %
Link to C# source.