/// <summary>
/// User has clicked the PMT compute Button
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void mBtnPMTCompute_Click(object sender, EventArgs e)
{
TvmObject O = new TvmObject();
double Pmt;
bool Valid = true;
#region Verify Format
if ((double.TryParse(mN.Text, out double w)) == false)
{
mN.Text = "";
mN.Hint = "Invalid Input";
Valid = false;
}
if ((double.TryParse(mIY.Text, out double x)) == false)
{
mIY.Text = "";
mIY.Hint = "Invalid Input";
Valid = false;
}
if ((double.TryParse(mPV.Text, out double y)) == false)
{
mPV.Text = "";
mPV.Hint = "Invalid Input";
Valid = false;
}
if ((double.TryParse(mFV.Text, out double z)) == false)
{
mFV.Text = "";
mFV.Hint = "Invalid Input";
Valid = false;
}
#endregion
if (Valid == true)
{
O.N = double.Parse(mN.Text);
O.I = double.Parse(mIY.Text);
O.Pv = double.Parse(mPV.Text);
O.Fv = double.Parse(mFV.Text);
if (this.IsBegMode == true)
{
Pmt = PmtAdCompute(O);
}
else
{
Pmt = PmtCompute(O);
}
mOnPmtComptComplete.Invoke(this, new OnPmtComputeEventArgs(Pmt));
this.Dismiss();
}
}
/// <summary>
/// Computes the interest rate in a TVM equation, note that this method utilizes Newton's Method
/// to iterate through possible options to find the best fit as interest rate cannot be directly computed.
/// Regular Annuity or payment at end of the period.
/// </summary>
public static double ICompute(TvmObject obj)
{
var n = obj.N;
var pv = obj.Pv;
var pmt = obj.Pmt;
var fv = obj.Fv;
var type = 0;
var guess = 0.1;
try
{
int itrMax = 20;
double espMax = 1e-10;
double y, y1, rate = 0, f = 0, count = 0;
double i = guess;
f = Math.Pow(1 + i, n);
y = pv * f + pmt * ((f - 1) / i) * (1 + i * type) + fv;
//first derivative:
y1 = (f * ((pmt * n * type + n * pv) * Math.Pow(i, 2) + (pmt * n - pmt) * i - pmt) + pmt * i + pmt) / (Math.Pow(i, 3) + Math.Pow(i, 2));
rate = i - y / y1;
while ((Math.Abs(i - rate) > espMax) && (count < itrMax))
{
i = rate;
f = Math.Pow(1 + i, n);
y = pv * f + pmt * ((f - 1) / i) * (1 + i * type) + fv;
//first derivative:
y1 = (f * ((pmt * n * type + n * pv) * Math.Pow(i, 2) + (pmt * n - pmt) * i - pmt) + pmt * i + pmt) / (Math.Pow(i, 3) + Math.Pow(i, 2));
rate = i - y / y1;
++count;
}
i = rate;
return(i * 100);
}
catch
{
throw new System.ArgumentException();
}
}
public void PVAd2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 5,
I = 10,
Pv = 0,
Pmt = 10,
Fv = -350
};
//Act,
var result = Math.Round(PvAdCompute(obj), 4);
//Assert
Assert.AreEqual(175.6238, result);
}
public void PVAd_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 5,
I = 10,
Pv = 0,
Pmt = -10,
Fv = 200,
};
//Act,
var result = Math.Round(PvAdCompute(obj), 4);
//Assert
Assert.AreEqual(-82.4856, result);
}
public void IAd2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 15,
I = 0,
Pv = 100,
Pmt = 50,
Fv = -925,
};
//Act,
var result = Math.Round(IAdCompute(obj), 4);
//Assert
Assert.AreEqual(0.9519, result);
}
public void IAd_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 10,
I = 0,
Pv = -100,
Pmt = -10,
Fv = 1000,
};
//Act,
var result = Math.Round(IAdCompute(obj), 4);
//Assert
Assert.AreEqual(20.9629, result);
}
public void NAd2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 0.00,
I = 12,
Pv = 200,
Pmt = 5,
Fv = -400,
};
//Act,
var result = Math.Round(NAdCompute(obj), 4);
//Assert
Assert.AreEqual(5.2394, result);
}
public void FVAd_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 5,
I = 10,
Pv = -5,
Pmt = -10,
Fv = 0,
};
//Act,
var result = Math.Round(FvAdCompute(obj), 4);
//Assert
Assert.AreEqual(75.2087, result);
}
public void PMT2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 15,
I = 5,
Pv = -30,
Pmt = 0,
Fv = 250,
};
//Act,
var result = Math.Round(PmtCompute(obj), 4);
//Assert
Assert.AreEqual(-8.6953, result);
}
public void PV2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 8,
I = 12,
Pv = 0,
Pmt = 10,
Fv = -500,
};
//Act,
var result = Math.Round(PvCompute(obj), 4);
//Assert
Assert.AreEqual(152.2652, result);
}
public void I6_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 5,
I = 0,
Pv = -10,
Pmt = 5,
Fv = 0,
};
//Act,
var result = Math.Round(ICompute(obj), 4);
//Assert
Assert.AreEqual(41.0415, result);
}
public void I4_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 2,
I = 0,
Pv = -10,
Pmt = 10,
Fv = 0,
};
//Act,
var result = Math.Round(ICompute(obj), 4);
//Assert
Assert.AreEqual(61.8034, result);
}
public void I2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 12,
I = 0,
Pv = 140,
Pmt = 50,
Fv = -1000,
};
//Act,
var result = Math.Round(ICompute(obj), 4);
//Assert
Assert.AreEqual(4.3512, result);
}
public void N2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 0.00,
I = 15,
Pv = 200,
Pmt = 15,
Fv = -750,
};
//Act,
var result = Math.Round(NCompute(obj), 4);
//Assert
Assert.AreEqual(7.4516, result);
}
public void N_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 0.00,
I = 15,
Pv = -250,
Pmt = -15,
Fv = 750,
};
//Act,
var result = Math.Round(NCompute(obj), 4);
//Assert
Assert.AreEqual(6.3487, result);
}
public void PMTAd2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 10,
I = 15,
Pv = 20,
Pmt = 0,
Fv = -346,
};
//Act,
var result = Math.Round(PmtAdCompute(obj), 4);
//Assert
Assert.AreEqual(11.3532, result);
}
public void FV2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 10,
I = 6,
Pv = -25,
Pmt = -50,
Fv = 0,
};
//Act,
var result = Math.Round(FvCompute(obj), 4);
//Assert
Assert.AreEqual(703.8109, result);
}
public void FVAd2_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 65,
I = 8,
Pv = 1000,
Pmt = 100,
Fv = 0,
};
//Act,
var result = Math.Round(FvAdCompute(obj), 4);
//Assert
Assert.AreEqual(-348282.6396, result);
}
public void NAd_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 0.00,
I = 10,
Pv = -100,
Pmt = -10,
Fv = 500,
};
//Act,
var result = Math.Round(NAdCompute(obj), 4);
//Assert
Assert.AreEqual(11.1882, result);
}
public void PMTAd_Compute()
{
//Arrange,
var obj = new TvmObject
{
N = 10,
I = 10,
Pv = -15,
Pmt = 0,
Fv = 100,
};
//Act,
var result = Math.Round(PmtAdCompute(obj), 4);
//Assert
Assert.AreEqual(-3.4849, result);
}
/// <summary>
/// Computes the present value in a TVM equation. Regular Annuity or payment at end of the period.
/// </summary>
public static double PvCompute(TvmObject obj)
{
var n = obj.N;
var i = obj.I;
double pv = 0;
var pmt = obj.Pmt;
var fv = obj.Fv;
try
{
i = i / 100;
pv = (1 / i) * (Math.Pow((1 + i), (n * -1))) * (((-1 * fv) * i) - ((pmt * (Math.Pow((1 + i), n)))) + pmt);
return(pv);
}
catch
{
throw new System.ArgumentException();
}
}
/// <summary>
/// Computes the future value in a TVM equation. Annuity Due or payment at the beginning of the period.
/// </summary>
public static double FvAdCompute(TvmObject obj)
{
var n = obj.N;
var i = obj.I;
var pv = obj.Pv;
var pmt = obj.Pmt;
double fv = 0;
try
{
i = i / 100;
fv = (1 / i) * ((i * -1) * (pmt * Math.Pow((i + 1), n) - pmt + pv * Math.Pow((i + 1), n)) - pmt * Math.Pow((i + 1), n) + pmt);
return(fv);
}
catch
{
throw new System.ArgumentException();
}
}
/// <summary>
/// Computes the payment in a TVM equation. Annuity Due or payment at the beginning of the period.
/// </summary>
public static double PmtAdCompute(TvmObject obj)
{
var n = obj.N;
var i = obj.I;
var pv = obj.Pv;
double pmt = 0;
var fv = obj.Fv;
try
{
i = i / 100;
pmt = -1 * ((i * (fv + pv * Math.Pow((i + 1), n))) / (i * Math.Pow((i + 1), n) - i + Math.Pow((i + 1), n) - 1));
return(pmt);
}
catch
{
throw new System.ArgumentException();
}
}
/// <summary>
/// Computes the present value in a TVM equation. Annuity Due or payment at the beginning of the period.
/// </summary>
public static double PvAdCompute(TvmObject obj)
{
var n = obj.N;
var i = obj.I;
double pv = 0;
var pmt = obj.Pmt;
var fv = obj.Fv;
try
{
i = i / 100;
pv = (-1 * fv) * Math.Pow((i + 1), (n * -1)) - pmt + pmt * Math.Pow((i + 1), (n * -1)) - (pmt / i) + (pmt / i) * Math.Pow((i + 1), (n * -1));
return(pv);
}
catch
{
throw new System.ArgumentException();
}
}
//TVM *annuity due* calculations *BEG MODE*
/// <summary>
/// Computes the number of periods in a TVM equation. Annuity Due or payment at the beginning of the period.
/// </summary>
public static double NAdCompute(TvmObject obj)
{
double n = 0;
var i = obj.I;
var pv = obj.Pv;
var pmt = obj.Pmt;
var fv = obj.Fv;
try
{
i = i / 100;
n = Math.Log((((fv * -1) * (i)) + (i * pmt) + pmt) / ((i * pv) + (i * pmt) + pmt)) / (Math.Log(1 + i));
return(n);
}
catch
{
throw new System.ArgumentException();
}
}
/// <summary>
/// User has clicked the PMT compute Button
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
private void mBtnPMTCompute_Click(object sender, EventArgs e)
{
TvmObject O = new TvmObject();
double Pmt;
bool Valid = true;
#region Verify Format
if ((double.TryParse(mN.Text, out double w)) == false)
{
mN.Hint = "Invalid Input";
Valid = false;
}
if ((double.TryParse(mIY.Text, out double x)) == false)
{
mIY.Hint = "Invalid Input";
Valid = false;
}
if ((double.TryParse(mPV.Text, out double y)) == false)
{
mPV.Hint = "Invalid Input";
Valid = false;
}
if ((double.TryParse(mFV.Text, out double z)) == false)
{
mFV.Hint = "Invalid Input";
Valid = false;
}
#endregion
if (Valid == true)
{
O.N = double.Parse(mN.Text);
O.I = double.Parse(mIY.Text);
O.Pv = double.Parse(mPV.Text);
O.Fv = double.Parse(mFV.Text);
Pmt = PmtCompute(O);
mPMT.Text = Pmt.ToString();
}
}
/// <summary>
/// This Method preforms an Amortization Calculation (giving the user the balance, interest paid, and principle paid
/// between time p1 and p2. Note that p1 & p2 and be period 1 (start of loan) and period 10 (potential end of loan) or
/// P1 & P2 could both be for period five which would provide the balance at P5, as well as principle and interest paid for that period.
/// </summary>
/// <param name="tObj"></param>
/// <param name="aObj"></param>
/// <returns></returns>
public static AmortObject AmortCompute(TvmObject tObj, AmortObject aObj)
{
var r = tObj.I / 100;
aObj.C_Bal = tObj.Pv;
for (int i = 1; i <= aObj.P2; i++)
{
aObj.I_Paid = aObj.C_Bal * r;
aObj.P_Paid = tObj.Pmt + aObj.I_Paid;
aObj.C_Bal = aObj.C_Bal + aObj.P_Paid;
if (i >= aObj.P1)
{
aObj.IntPaid = aObj.IntPaid + aObj.I_Paid;
aObj.PrnPaid = aObj.PrnPaid + aObj.P_Paid;
}
}
aObj.EndBal = aObj.C_Bal;
aObj.IntPaid = aObj.IntPaid * -1;
return(aObj);
}
public void Amort3()
{
//Arrange,
var tObj = new TvmObject();
tObj.N = 10;
tObj.I = 10;
tObj.Pv = 250;
tObj.Pmt = -40.6863;
tObj.Fv = 0;
var obj = new AmortObject();
obj.P1 = 3;
obj.P2 = 3;
//Act,
var result = AmortCompute(tObj, obj);
//Assert
Assert.AreEqual(198.0783, Math.Round(result.EndBal, 4)); //calc returned 198.0784 which is strange. Because a double is used it is likely more accurate than the BA II Plus.
Assert.AreEqual(-18.9804, Math.Round(result.PrnPaid, 4));
Assert.AreEqual(-21.7059, Math.Round(result.IntPaid, 4));
}
public void Amort6() // With + payment and -FV
{
//Arrange,
var tObj = new TvmObject();
tObj.N = 10;
tObj.I = 10;
tObj.Pv = 250;
tObj.Pmt = 10;
tObj.Fv = -907.8099;
var obj = new AmortObject();
obj.P1 = 1;
obj.P2 = 1;
//Act,
var result = AmortCompute(tObj, obj);
//Assert
Assert.AreEqual(285.0000, Math.Round(result.EndBal, 4));
Assert.AreEqual(35.0000, Math.Round(result.PrnPaid, 4));
Assert.AreEqual(-25.0000, Math.Round(result.IntPaid, 4));
}
public void Amort4() //With Balloon Payment
{
//Arrange,
var tObj = new TvmObject();
tObj.N = 10;
tObj.I = 10;
tObj.Pv = 250;
tObj.Pmt = -40.0589;
tObj.Fv = -10;
var obj = new AmortObject();
obj.P1 = 3;
obj.P2 = 9;
//Act,
var result = AmortCompute(tObj, obj);
//Assert
Assert.AreEqual(45.5080, Math.Round(result.EndBal, 4));
Assert.AreEqual(-172.8683, Math.Round(result.PrnPaid, 4));
Assert.AreEqual(-107.5440, Math.Round(result.IntPaid, 4));
}
