Index was out of range. Must be non-negative and less than t

Question

.cs

 

int loan_amt = Int32.Parse(txtLoan_Amount.Text);
double Int_rate = Double.Parse(TxtInterest_Rate.Text);
string freq = DdlFrequency.SelectedItem.Text;
int duration = Int32.Parse(txtDuration.Text);

double Remaining_amt = Int32.Parse( txtLoan_Amount.Text);


while (Remaining_amt > 0)
{
for(int i =1; i<= duration; i++)
{

double monthly_installment = Math.Round(Financial.Pmt((Int_rate / 100) / 12, duration, -(loan_amt)), 0, MidpointRounding.AwayFromZero);
double interest_amt= Math.Round((Remaining_amt * Int_rate )/100/12 ,0,MidpointRounding.AwayFromZero);
GridView1.Rows[i].Cells[1].Text = i.ToString();
Remaining_amt= Remaining_amt- (monthly_installment-interest_amt);
GridView1.Rows[i].Cells[2].Text = Remaining_amt.ToString();
GridView1.Rows[i].Cells[3].Text = (monthly_installment - interest_amt).ToString();
GridView1.Rows[i].Cells[4].Text = interest_amt.ToString();
GridView1.Rows[i].Cells[5].Text = "";
}
}

 

.aspx

 

<asp:GridView ID="GridView1" runat="server" CellPadding="4"
ForeColor="#333333" GridLines="None">
<AlternatingRowStyle BackColor="White" />
<Columns>
<asp:BoundField HeaderStyle-Width="120px" HeaderText="Installment No" DataField="" />
<asp:BoundField HeaderStyle-Width="120px" HeaderText=" Remaining Amount" DataField="" />
<asp:BoundField HeaderStyle-Width="120px" HeaderText=" Principle" DataField="" />
<asp:BoundField HeaderStyle-Width="120px" HeaderText=" Interest" DataField="" />
<asp:BoundField HeaderStyle-Width="120px" HeaderText=" Total Emi" DataField="" />
</Columns>
 </asp:GridView>