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100 lines
2.4 KiB
ObjectPascal
100 lines
2.4 KiB
ObjectPascal
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unit PresentValueUnit;
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{$mode objfpc}{$H+}
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interface
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uses
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Classes, SysUtils, FileUtil, LResources, Forms, Controls, Graphics, Dialogs,
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StdCtrls, ExtCtrls;
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type
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{ TPresentValueFrm }
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TPresentValueFrm = class(TForm)
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ResetBtn: TButton;
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ComputeBtn: TButton;
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ReturnBtn: TButton;
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FutureEdit: TEdit;
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PaymentEdit: TEdit;
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NPeriodsEdit: TEdit;
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RateEdit: TEdit;
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PresentEdit: TEdit;
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Label1: TLabel;
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Label2: TLabel;
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Label3: TLabel;
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Label4: TLabel;
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Label5: TLabel;
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Memo1: TMemo;
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PayTimeGrp: TRadioGroup;
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procedure ComputeBtnClick(Sender: TObject);
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procedure FormShow(Sender: TObject);
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procedure ResetBtnClick(Sender: TObject);
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function PresentValue(Rate: Extended; NPeriods: Integer; Payment, FutureValue:
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Extended; PaymentTime: TPaymentTime): Extended;
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private
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{ private declarations }
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public
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{ public declarations }
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end;
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var
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PresentValueFrm: TPresentValueFrm;
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implementation
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{ TPresentValueFrm }
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procedure TPresentValueFrm.ResetBtnClick(Sender: TObject);
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begin
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FutureEdit.Text := '';
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PaymentEdit.Text := '';
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NPeriodsEdit.Text := '';
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RateEdit.Text := '';
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PresentEdit.Text := '';
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end;
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procedure TPresentValueFrm.FormShow(Sender: TObject);
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begin
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ResetBtnClick(self);
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end;
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procedure TPresentValueFrm.ComputeBtnClick(Sender: TObject);
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VAR
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Rate, Payment, PresentVal, FutureVal, Interest : Extended;
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NPeriods, When : integer;
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Time : TPaymentTime;
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begin
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If PayTimeGrp.ItemIndex = 0 then Time := ptStartofPeriod else
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Time := ptEndofPeriod;
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FutureVal := StrToFloat(FutureEdit.Text);
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Rate := StrToFloat(RateEdit.Text);
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NPeriods := StrToInt(NPeriodsEdit.Text);
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Payment := StrToFloat(PaymentEdit.Text);
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PresentVal := PresentValue(Rate, NPeriods, Payment, FutureVal, Time);
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PresentEdit.Text := FloatToStr(PresentVal);
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end;
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function TPresentValueFrm.PresentValue(Rate: Extended; NPeriods: Integer; Payment, FutureValue:
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Extended; PaymentTime: TPaymentTime): Extended;
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var
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Annuity, CompoundRN: Extended;
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begin
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if Rate <= -1.0 then ShowMessage('ERROR! PresentValue Rate <= -1.-');
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Annuity := Annuity2(Rate, NPeriods, PaymentTime, CompoundRN);
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if CompoundRN > 1.0E16 then
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PresentValue := -(Payment / Rate * Integer(PaymentTime) * Payment)
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else
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PresentValue := (-Payment * Annuity - FutureValue) / CompoundRN
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end;
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initialization
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{$I presentvalueunit.lrs}
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end.
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