You can download the application here (note: only works on Macs). For questions, click on the chat bubble on the lower left corner of the screen 🙂
Background
Compound rate calculation is relatively simple, but compound rate calculation combined with a fixed annual deposition/addition is much more difficult. Below is an formulation of compound rate calculation with a fixed annual deposition/addition:
It would be too time-consuming to go through the above calculation every time we decide how much to put into our savings accounts, pensions etc. However, without going through the exact calculation, it is very easy to underestimate the magnitude of our accumulations in the long run when interest is compounded. Hence, I developed the above simple application, with the hopes that the graphical and tabular information will be especially helpful in understanding the power of compound interest (with a fixed annual addition).
This application allows the user to input four variable inputs: the principle amount in the account, the annual deposition/contribution, the number of years elapsed, and the annual interest rate (compounded annually).
The application outputs three pieces of information:
- the total amount after the number of years elapsed
- a graph plotting total amount vs years elapsed (the graph also displays the total amount deposited for comparison with the total amount)
- a table containing below columns:
- Year
- Total Savings
- Total Amount Deposited
- Total Interest Gained
- Total Savings as a ratio of Total Amount Deposited
Source Code
classdef InterestRate < matlab.apps.AppBase
% Properties that correspond to app components
properties (Access = public)
UIFigure matlab.ui.Figure
GridLayout matlab.ui.container.GridLayout
LeftPanel matlab.ui.container.Panel
Panel matlab.ui.container.Panel
PrincipalAmountEditFieldLabel matlab.ui.control.Label
PrincipalAmountEditField matlab.ui.control.NumericEditField
NumberofYearsElapsedEditFieldLabel matlab.ui.control.Label
NumberofYearsElapsedEditField matlab.ui.control.NumericEditField
YearlyAdditionFixedEditFieldLabel matlab.ui.control.Label
YearlyAdditionFixedEditField matlab.ui.control.NumericEditField
InterestRateEditFieldLabel matlab.ui.control.Label
InterestRateEditField matlab.ui.control.NumericEditField
CalculateTotalAmountafterNumbersofYearsElapsedButton matlab.ui.control.Button
Output matlab.ui.control.EditField
InterestRateEditField_2Label_2 matlab.ui.control.Label
UITable matlab.ui.control.Table
RightPanel matlab.ui.container.Panel
UIAxes matlab.ui.control.UIAxes
end
% Properties that correspond to apps with auto-reflow
properties (Access = private)
onePanelWidth = 576;
end
% Callbacks that handle component events
methods (Access = private)
% Button pushed function:
% CalculateTotalAmountafterNumbersofYearsElapsedButton
function CalculateTotalAmountafterNumbersofYearsElapsedButtonPushed(app, event)
% Naming Variables
principal_amount = app.PrincipalAmountEditField.Value;
yearly_addition = app.YearlyAdditionFixedEditField.Value;
number_years = app.NumberofYearsElapsedEditField.Value;
interest_rate = app.InterestRateEditField.Value;
%% Computation
total_amount=principal_amount;
temp_matrix_zeros=zeros([1 number_years]);
temp_matrix_zeros_2=zeros([1 number_years]);
total_yearly_addition=principal_amount;
for n=1:number_years
total_amount=(yearly_addition+total_amount)*(1+interest_rate);
temp_matrix_zeros(1,n)=total_amount;
total_yearly_addition=yearly_addition+total_yearly_addition;
temp_matrix_zeros_2(1,n)=total_yearly_addition;
end
app.Output.Value = string(total_amount);
%% Displaying a graph of total amount vs year elapsed
x_axis=1:number_years;
plot(app.UIAxes,x_axis,temp_matrix_zeros,'r');
hold (app.UIAxes,"on");
plot(app.UIAxes,x_axis,temp_matrix_zeros_2,'k');
hold (app.UIAxes,"off");
legend(app.UIAxes,'Total Savings','Total Amount Deposited');
%% Displaying further processed data in tabular format
matrix=round([1:number_years;temp_matrix_zeros;temp_matrix_zeros_2;temp_matrix_zeros-temp_matrix_zeros_2]);
matrix_2=temp_matrix_zeros./temp_matrix_zeros_2;
matrix=vertcat(matrix,matrix_2);
matrix=transpose(matrix);
matrix=(array2table(matrix,'VariableNames',{'Year';'Total Savings'; 'Total Amount Deposited'; 'Total Interest Gained'; 'Total Savings As A Ratio of Total Amount Deposited'}));
app.UITable.Data = matrix;
app.UITable.ColumnName = matrix.Properties.VariableNames;
format bank
end
% Changes arrangement of the app based on UIFigure width
function updateAppLayout(app, event)
currentFigureWidth = app.UIFigure.Position(3);
if(currentFigureWidth <= app.onePanelWidth)
% Change to a 2x1 grid
app.GridLayout.RowHeight = {502, 502};
app.GridLayout.ColumnWidth = {'1x'};
app.RightPanel.Layout.Row = 2;
app.RightPanel.Layout.Column = 1;
else
% Change to a 1x2 grid
app.GridLayout.RowHeight = {'1x'};
app.GridLayout.ColumnWidth = {412, '1x'};
app.RightPanel.Layout.Row = 1;
app.RightPanel.Layout.Column = 2;
end
end
end
% Component initialization
methods (Access = private)
% Create UIFigure and components
function createComponents(app)
% Create UIFigure and hide until all components are created
app.UIFigure = uifigure('Visible', 'off');
app.UIFigure.AutoResizeChildren = 'off';
app.UIFigure.Position = [100 100 886 502];
app.UIFigure.Name = 'Interest Rate Calculation With Yearly Deposition (Compound Interest)';
app.UIFigure.SizeChangedFcn = createCallbackFcn(app, @updateAppLayout, true);
app.UIFigure.Scrollable = 'on';
% Create GridLayout
app.GridLayout = uigridlayout(app.UIFigure);
app.GridLayout.ColumnWidth = {412, '1x'};
app.GridLayout.RowHeight = {'1x'};
app.GridLayout.ColumnSpacing = 0;
app.GridLayout.RowSpacing = 0;
app.GridLayout.Padding = [0 0 0 0];
app.GridLayout.Scrollable = 'on';
% Create LeftPanel
app.LeftPanel = uipanel(app.GridLayout);
app.LeftPanel.Layout.Row = 1;
app.LeftPanel.Layout.Column = 1;
% Create Panel
app.Panel = uipanel(app.LeftPanel);
app.Panel.TitlePosition = 'centertop';
app.Panel.Scrollable = 'on';
app.Panel.Position = [7 282 399 210];
% Create PrincipalAmountEditFieldLabel
app.PrincipalAmountEditFieldLabel = uilabel(app.Panel);
app.PrincipalAmountEditFieldLabel.HorizontalAlignment = 'right';
app.PrincipalAmountEditFieldLabel.Position = [14 178 97 22];
app.PrincipalAmountEditFieldLabel.Text = 'Principal Amount';
% Create PrincipalAmountEditField
app.PrincipalAmountEditField = uieditfield(app.Panel, 'numeric');
app.PrincipalAmountEditField.Limits = [0 Inf];
app.PrincipalAmountEditField.ValueDisplayFormat = '%.0f';
app.PrincipalAmountEditField.Position = [173 178 100 22];
app.PrincipalAmountEditField.Value = 1000;
% Create NumberofYearsElapsedEditFieldLabel
app.NumberofYearsElapsedEditFieldLabel = uilabel(app.Panel);
app.NumberofYearsElapsedEditFieldLabel.HorizontalAlignment = 'right';
app.NumberofYearsElapsedEditFieldLabel.Position = [14 113 142 22];
app.NumberofYearsElapsedEditFieldLabel.Text = 'Number of Years Elapsed';
% Create NumberofYearsElapsedEditField
app.NumberofYearsElapsedEditField = uieditfield(app.Panel, 'numeric');
app.NumberofYearsElapsedEditField.Limits = [0 Inf];
app.NumberofYearsElapsedEditField.RoundFractionalValues = 'on';
app.NumberofYearsElapsedEditField.ValueDisplayFormat = '%.0f';
app.NumberofYearsElapsedEditField.Position = [173 113 100 22];
app.NumberofYearsElapsedEditField.Value = 20;
% Create YearlyAdditionFixedEditFieldLabel
app.YearlyAdditionFixedEditFieldLabel = uilabel(app.Panel);
app.YearlyAdditionFixedEditFieldLabel.HorizontalAlignment = 'right';
app.YearlyAdditionFixedEditFieldLabel.Position = [14 145 124 22];
app.YearlyAdditionFixedEditFieldLabel.Text = 'Yearly Addition (Fixed)';
% Create YearlyAdditionFixedEditField
app.YearlyAdditionFixedEditField = uieditfield(app.Panel, 'numeric');
app.YearlyAdditionFixedEditField.Limits = [0 Inf];
app.YearlyAdditionFixedEditField.ValueDisplayFormat = '%.0f';
app.YearlyAdditionFixedEditField.Position = [173 145 100 22];
app.YearlyAdditionFixedEditField.Value = 1200;
% Create InterestRateEditFieldLabel
app.InterestRateEditFieldLabel = uilabel(app.Panel);
app.InterestRateEditFieldLabel.HorizontalAlignment = 'right';
app.InterestRateEditFieldLabel.Position = [14 81 89 22];
app.InterestRateEditFieldLabel.Text = 'Interest Rate %';
% Create InterestRateEditField
app.InterestRateEditField = uieditfield(app.Panel, 'numeric');
app.InterestRateEditField.Limits = [0 Inf];
app.InterestRateEditField.Position = [173 81 100 22];
app.InterestRateEditField.Value = 0.05;
% Create CalculateTotalAmountafterNumbersofYearsElapsedButton
app.CalculateTotalAmountafterNumbersofYearsElapsedButton = uibutton(app.Panel, 'push');
app.CalculateTotalAmountafterNumbersofYearsElapsedButton.ButtonPushedFcn = createCallbackFcn(app, @CalculateTotalAmountafterNumbersofYearsElapsedButtonPushed, true);
app.CalculateTotalAmountafterNumbersofYearsElapsedButton.IconAlignment = 'center';
app.CalculateTotalAmountafterNumbersofYearsElapsedButton.Position = [14 49 317 22];
app.CalculateTotalAmountafterNumbersofYearsElapsedButton.Text = 'Calculate Total Amount after Numbers of Years Elapsed';
% Create Output
app.Output = uieditfield(app.Panel, 'text');
app.Output.Editable = 'off';
app.Output.HorizontalAlignment = 'center';
app.Output.Position = [173 17 100 22];
% Create InterestRateEditField_2Label_2
app.InterestRateEditField_2Label_2 = uilabel(app.Panel);
app.InterestRateEditField_2Label_2.HorizontalAlignment = 'right';
app.InterestRateEditField_2Label_2.Position = [16 17 87 22];
app.InterestRateEditField_2Label_2.Text = 'Total Amount =';
% Create UITable
app.UITable = uitable(app.LeftPanel);
app.UITable.ColumnName = {''};
app.UITable.RowName = {};
app.UITable.ColumnSortable = true;
app.UITable.FontSize = 10;
app.UITable.Position = [7 16 399 259];
% Create RightPanel
app.RightPanel = uipanel(app.GridLayout);
app.RightPanel.Layout.Row = 1;
app.RightPanel.Layout.Column = 2;
% Create UIAxes
app.UIAxes = uiaxes(app.RightPanel);
title(app.UIAxes, 'Amount Deposited vs Total Amount ')
xlabel(app.UIAxes, 'Time (Years)')
ylabel(app.UIAxes, 'Amount')
app.UIAxes.PlotBoxAspectRatio = [1 1.05109489051095 1];
app.UIAxes.Position = [9 8 459 487];
% Show the figure after all components are created
app.UIFigure.Visible = 'on';
end
end
% App creation and deletion
methods (Access = public)
% Construct app
function app = InterestRate
% Create UIFigure and components
createComponents(app)
% Register the app with App Designer
registerApp(app, app.UIFigure)
if nargout == 0
clear app
end
end
% Code that executes before app deletion
function delete(app)
% Delete UIFigure when app is deleted
delete(app.UIFigure)
end
end
end
2 comments
Long time supporter, and thought I’d drop a comment.
Your wordpress site is very sleek – hope you don’t mind me asking what theme you’re using?
(and don’t mind if I steal it? :P)
I just launched my site –also built in wordpress
like yours– but the theme slows (!) the site down quite a bit.
In case you have a minute, you can find it by searching
for “royal cbd” on Google (would appreciate any feedback) – it’s
still in the works.
Keep up the good work– and hope you all take
care of yourself during the coronavirus scare!
Heya! Thanks for your comment, I have replied to your email!