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基於PHP的攤銷表

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發布： 2016-08-08 09:20:09

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Amortization Table

The Function of Recursive Function

What’s the Recursive Function?

Returning Values from a Function

Often, simply relying on a function to do something is insufficient; a script’s outcome might depend on a function’s outcome, or on changes in data resulting from its execution. Yet variable scoping prevents information from easily being passed from a function body back to its caller, so how can we accomplish this? You can pass data back to the caller by way of the return keyword.

Recursive functions, or functions that call themselves, offer considerable practical value to the programmer and are used to divide an otherwise complex problem into a simple case, reiterating that case until the problem is resolved.

Practically every introductory recursion example involves factorial computation. Yawn. Let’s do something a tad more practical and create a loan payment calculator. Specifically, the following example uses recursion to create a payment schedule, telling you the principal and interest amounts required of each payment installment to repay the loan. The recursive function, amortizationTable(),It takes as input four arguments:

paymentNum, which identifies the payment number, periodicPayment, which carries the total monthly payment, balance, which indicates the remaining loan balance, and monthlyInterest, which determines the monthly interest percentage rate. These items are designated or deter- mined in the script listed below here:

<code><span><?php</span><span><span>function</span><span>amortizationTable</span><span>(<span>$paymentNum</span>,<span>$periodicPayment</span>,<span>$balance</span>,<span>$monthlyInterest</span>)</span>
    {</span><span>$paymentInterest</span>=round(<span>$balance</span>*<span>$monthlyInterest</span>,<span>2</span>);
        <span>$paymentPrincipal</span>=round(<span>$periodicPayment</span>-<span>$paymentInterest</span>,<span>2</span>);
        <span>$newBalance</span>=round(<span>$balance</span>-<span>$paymentPrincipal</span>,<span>2</span>);
        <span>print</span><span>"  <tr>
                    <td>$paymentNum</td>
                    <td>\$"</span>.number_format(<span>$balance</span>,<span>2</span>).<span>"</td>
                    <td>\$"</span>.number_format(<span>$periodicPayment</span>,<span>2</span>).<span>"</td>
                    <td>\$"</span>.number_format(<span>$paymentInterest</span>,<span>2</span>).<span>"</td>
                    <td>\$"</span>.number_format(<span>$paymentPrincipal</span>,<span>2</span>).<span>"</td>
                </tr>"</span>;
        <span>#If balance not yet zero ,recursively call amortizationTable()</span><span>if</span>(<span>$newBalance</span>><span>0</span>)
        {
            <span>$paymentNum</span>++;
            amortizationTable(<span>$paymentNum</span>,<span>$periodicPayment</span>,<span>$newBalance</span>,<span>$monthlyInterest</span>);
        }
        <span>else</span>
        {
            <span>exit</span>;
        }
    }<span>#end amortizationTable()</span><span>?></span><span><?php</span><span>#load balance</span><span>$balance</span>=<span>200000.0</span>;

    <span>#load interest rate</span><span>$interestRate</span>=<span>.0575</span>;

    <span>#monthly interest rate</span><span>$monthlyInterest</span>=<span>.0575</span>/<span>12</span>;

    <span>#Term length of the load, in years.</span><span>$termLength</span>=<span>30</span>;

    <span>#Number of payments per year.</span><span>$paymentsPerYear</span>=<span>12</span>;

    <span>#payment iteration</span><span>$paymentNumber</span>=<span>1</span>;

    <span>#Perform preliminary calculations</span><span>$totalPayments</span>=<span>$termLength</span>*<span>$paymentsPerYear</span>;
    <span>$intCal</span>=<span>1</span>+<span>$interestRate</span>/<span>$paymentsPerYear</span>;
    <span>$periodicPayment</span>=<span>$balance</span>*pow(<span>$intCal</span>,<span>$totalPayments</span>)*(<span>$intCal</span>-<span>1</span>)/(pow(<span>$intCal</span>,<span>$totalPayments</span>)-<span>1</span>);
    <span>$periodicPayment</span>=round(<span>$periodicPayment</span>,<span>2</span>);

    <span>#create table</span><span>echo</span><span>"<table width='50%' align ='center' border='1'>"</span>;
    <span>print</span><span>"<tr>
          <th>Payment Number</th><th>Balance</th>
          <th>Payment</th><th>Interest</th><th>Principal</th>
          </tr>"</span>;
    <span>#call recursive function</span>
    amortizationTable(<span>$paymentNumber</span>,<span>$periodicPayment</span>,<span>$balance</span>,<span>$monthlyInterest</span>);
    <span>#close table</span><span>print</span><span>"</table>"</span>;</code>

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