why is my plot not showing lines

%This script is to solve for the investment of $50

%with an interest of 1% or 0.01 the equation uses the

% A * (1 + r) .^ n equation of interest with investment

%Script wrote by Doyouknow

format bank

monthlyInvestment = 50; %monthlyInvestment = 50;

interestRate = 0.01; %interestRate = 0.01;

monthEndBalance = 0;

disp('Month Month End Balance')

figure;

for month = 1:12

hold on;

monthEndBalance = monthEndBalance + (monthlyInvestment * (1 + interestRate) .^ month);

fprintf([num2str(month)]), disp(monthEndBalance(:))

plot (month,monthEndBalance,'r.')

title('Plot of Investment') %Testing out to see if i can plot

xlabel('Month (month)') %using the given data so far not

ylabel('Year (monthEndBalance)')

xticks (1:12) %sets the x values to be 1 - 12 to represent the graph

end

Answer 1

[Ankit]

Edited on 12.09.2022

Problem in your script is that you are not storing your results, values are updated in your "for loop"

%This script is to solve for the investment of $50 
%with an interest of 1% or 0.01 the equation uses the 
%  A  * (1 + r) .^ n equation of interest with investment
%Script wrote by Doyouknow
format bank
monthlyInvestment = 50; %monthlyInvestment = 50;
interestRate = 0.01; %interestRate = 0.01;
j = 1;
monthEndBalance =zeros(1,12);
prevmonthEndBalance = 0;
disp('Month   Month End Balance')

Month   Month End Balance

figure; 
month = 1:12;
for i = 1:length(month)
monthEndBalance(i) = prevmonthEndBalance + (monthlyInvestment * (1 + interestRate) .^ i);  
prevmonthEndBalance = monthEndBalance(i);
fprintf([num2str(month(i)) '-' num2str(monthEndBalance(month(i))) '\n'])
end

1-50.5
2-101.505
3-153.02
4-205.0503
5-257.6008
6-310.6768
7-364.2835
8-418.4264
9-473.1106
10-528.3417
11-584.1252
12-640.4664

plot (month,monthEndBalance);hold on
title('Plot of Investment') %Testing out to see if i can plot
xlabel('Month (month)')     %using the given data so far not
ylabel('Year (monthEndBalance)')
xticks (1:12) %sets the x values to be 1 - 12 to represent the graph

[Doyouknow]

Oooooo so it’s best to not use a for loop

Got it but is it possible to graph with a for loop? But I see with the hold on that will hold the values and save it for the graph. Alright I think I am seeing it thanks!

[Doyouknow]

Only issue I noticed is that the values are wrong. They are calculated incorrectly from what I am seeing more in the code you showed doesn’t work with the values I am attempting to get

[Ankit]

@Doyouknow Please check the updated solution.

Answer 2

[chrisw23]

Each plot call (loop) creates a line with one point. ( debug by look at the Figure.Children.Children property or save the return value of plot() )

This results in a 12×1 Line array and not a single line as you expected. Precalculate your data before plotting or try to use an animated line and add points in your loop.