"button2"
By GGMethos (https://pastebin.com/u/GGMethos)

URL: https://pastebin.com/nBqscHfh
Created on: Saturday 8th of March 2014 12:02:13 PM CDT
Retrieved on: Monday 26 of October 2020 05:55:49 AM UTC


private: System::Void button2_Click(System::Object^  sender, System::EventArgs^  e) {
				 if (textBox2->Text == "" && textBox1->Text != "" && textBox3->Text != "" && textBox4->Text != "")
				 {
					 double loanAmount2 = System::Convert::ToDouble(textBox1->Text);
					 double payment2 = System::Convert::ToDouble(textBox4->Text);
					 double numberOfMonths2 = System::Convert::ToDouble(textBox3->Text);

					 double initial2 = (2 * (numberOfMonths2 * payment2 - loanAmount2) / (numberOfMonths2 * loanAmount2));
					 double rOld2 = (initial2 * (pow((1 + initial2), numberOfMonths2)) / ((pow((1 + initial2), numberOfMonths2) - 1))) - (payment2 / loanAmount2);

					 double b2 = payment2 * pow((1. + rOld2), -numberOfMonths2);
					 double c2 = (rOld2 * loanAmount2);
					 double num2 = payment2 - (b2 - c2);
					 double denom2 = numberOfMonths2 * (payment2 * pow((1. + rOld2), (-numberOfMonths2 - 1)) - loanAmount2);
					 bool terminate2 = false;

				     double rNew2;
					 while (terminate2 == false)
					 { //terminating factor to exit the loop
						 rNew2 = rOld2 - (num2 / denom2);
						 if (fabs(rNew2 - rOld2) >= 0.01) //loops until difference is less than .01, then terminates
						 {
							 rOld2 = rNew2;
							 
						 }
						 else
						 {
							 terminate2 = true;
						 }
						 textBox2->Text = System::Convert::ToString(rNew2); //outputs desired results
					 }
					 }

				 else{
					 std::cout << "Something went wrong! Please check the button you pressed and what values you entered! You may have entered in a value for what you are calculating, which is not allowed. The textbox for the ouput needs to be cleared before you call the function." << std::endl;
					 errorProvider1->SetError(textBox2, "Please keep this blank to calculate the interest rate."); //error check
				  }
	}