Not able to see where the index is going past 5

load('Motor_Data.mat'); 
fprintf('Available motors:\n');
for i = 1:length(Names)
    fprintf('%d: %s\n', i, Names(i));
end
motor_index = input('Select a motor by entering its number: ');
mass = input('Enter the mass to be lifted (in kg): ');
height = input('Enter the height to lift the mass (in meters): ');
%Says this is where it errors
motor_name = Names(motor_index);    %HERE
power = Specs(1, motor_index);  
efficiency = Specs(2, motor_index);  
% Calculate output power
efficiency_decimal = efficiency / 100;
output_power = efficiency_decimal * power;  
g = 9.81;  
energy_required = mass * g * height;  
time = energy_required / output_power; 
fprintf('Motor: %s\n', motor_name);
fprintf('Load lifted: %.2f kg\n', mass);
fprintf('Height lifted: %.2f meters\n', height);
fprintf('Time to lift the load: %.2f seconds\n', time);
%Task 2
mass = input('Enter the mass to be lifted by all motors (in kg): ');
height = input('Enter the height to lift the mass by all motors (in meters): ');
% Initialize results matrix
num_motors = length(Names);
results = zeros(5, num_motors);
% Calculate time for each motor
g = 9.81;  % Gravity constant
for i = 1:num_motors
    power = Specs(1, i);  % Power in watts
    efficiency = Specs(2, i);  % Efficiency in percentage
    efficiency_decimal = efficiency / 100;
    output_power = efficiency_decimal * power;
    
    % Energy required to lift mass
    energy_required = mass * g * height;
    
    % Time to lift
    time = energy_required / output_power;
    
    % Store results: power, efficiency, mass, height, time
    results(:, i) = [power; efficiency; mass; height; time];
end
% Export results to CSV file
csvwrite('Task2_Results.csv', results);
% Display the matrix to verify
disp('Results matrix:');
disp(results);
%Task 3
output_powers = Specs(1, :) .* (Specs(2, :) / 100);  % Output power for each motor
times = results(5, :);  % Time from the results matrix
scatter(output_powers, times, 'filled');
xlabel('Output Power (W)');
ylabel('Time to Lift Load (s)');
title('Motor Output Power vs. Time to Lift Load');
grid on;

[Aniket]

Hi @Sebastian,

It seems like the user input provided is out of bounds. This can be handled with a validation after user input to ensure the value is within limits.

Can you please state the exact error and provide the "Motor_Data.mat" file to diagnose this further ?

[Steven Lord]

What exactly did you type at this prompt?

motor_index = input('Select a motor by entering its number: ');

What is the size of the Names variable that I assume you loaded from the MAT-file? You did not attach the MAT-file so we cannot check for ourselves.

[Sebastian]

Your script errors on line 20. for here it would be line 10

Error: Index exceeds the number of array elements. Index must not exceed 5.

Im getting this error in matlab grader but not matlab.

[Cris LaPierre]

You cannot use input in MATLAB Grader, which is used in lines 6-8 & 23-24 here:

motor_index = input('Select a motor by entering its number: ');
mass = input('Enter the mass to be lifted (in kg): ');
height = input('Enter the height to lift the mass (in meters): ');
%----------------
mass = input('Enter the mass to be lifted by all motors (in kg): ');
height = input('Enter the height to lift the mass by all motors (in meters): ');

However, you'd get a different error message in Grader if you were using them.

Error using input

Support for user input is required, which is not available on this platform.

Please share the code you are trying to submit.

[Sebastian]

 load('Motor_Data.mat'); 

fprintf('Available motors:\n');
for i = 1:length(Names)
    fprintf('%d: %s\n', i, Names(i));
end
motor_index = input('Select a motor by entering its number: ');

mass = input('Enter the mass to be lifted (in kg): ');
height = input('Enter the height to lift the mass (in meters): ');

motor_name = Names(motor_index);
power = Specs(1, motor_index);  
efficiency = Specs(2, motor_index);  

% Calculate output power
efficiency_decimal = efficiency / 100;
output_power = efficiency_decimal * power;  

g = 9.81;  
energy_required = mass * g * height;  
time = energy_required / output_power; 

fprintf('Motor: %s\n', motor_name);
fprintf('Load lifted: %.2f kg\n', mass);
fprintf('Height lifted: %.2f meters\n', height);
fprintf('Time to lift the load: %.2f seconds\n', time);

%Task 2

mass = input('Enter the mass to be lifted by all motors (in kg): ');
height = input('Enter the height to lift the mass by all motors (in meters): ');

% Initialize results matrix
num_motors = length(Names);
results = zeros(5, num_motors);

% Calculate time for each motor
g = 9.81;  % Gravity constant
for i = 1:num_motors
    power = Specs(1, i);  % Power in watts
    efficiency = Specs(2, i);  % Efficiency in percentage
    efficiency_decimal = efficiency / 100;
    output_power = efficiency_decimal * power;
    
    % Energy required to lift mass
    energy_required = mass * g * height;
    
    % Time to lift
    time = energy_required / output_power;
    
    % Store results: power, efficiency, mass, height, time
    results(:, i) = [power; efficiency; mass; height; time];
end

% Export results to CSV file
csvwrite('Task2_Results.csv', results);

% Display the matrix to verify
disp('Results matrix:');
disp(results);
%Task 3
output_powers = Specs(1, :) .* (Specs(2, :) / 100);  % Output power for each motor
times = results(5, :);  % Time from the results matrix

scatter(output_powers, times, 'filled');
xlabel('Output Power (W)');
ylabel('Time to Lift Load (s)');
title('Motor Output Power vs. Time to Lift Load');
grid on;

[Cris LaPierre]

What is the result when you submit this in MATLAB Grader? You should be getting the error I mentioned about using input, and not one about indexing.

We need more details in order to help you out.

[Sebastian]

No error about using Inputs. Just the indexing saying the array cannot exceed 5

[Sebastian]

Load in the provided data file, Motor_Data.mat. Prompt the user to select one of the input motors for testing. Prompt the user to enter a mass to be lifted by the motor [kg] and the height that mass will be raised to [m]. Calculate the amount of time it will take for the selected motor to raise the inputted load to the specified height. Output to the command window the time it will take for the motor to raise the load. Include the motor’s name, the load lifted, and the height it was lifted to. This is the first part of the problem

[Cris LaPierre]

MATLAB Grader does not support prompting the user. Can you please share a screenshot of the entire problem?

[Sebastian]

Here is the entire problem

[Cris LaPierre]

Thank you. So far, this doesn't look like MATLAB Grader. How do you submit your code for grading?

[Sebastian]

This is just the prompt. The matlab code grader is through the Canvas software

[Cris LaPierre]

The prompt is helpful, but it would also be helpful to see the assessment page as well.

Answer 1

[Image Analyst]

Names only has 4 strings in it, not 5 so that's why you get the error. The code is not very robust. Here, I've improved it by giving a better error message if the user enters the wrong number (see the while loop). It works for me in desktop MATLAB.

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format short g;
format compact;

load('Motor_Data.mat');
motor_index = inf; % Initialize.
while motor_index >= numel(Names) || motor_index < 1
    fprintf('Available motors:\n');
    for k = 1:length(Names)
        fprintf('%d: %s\n', k, Names(k));
    end
    motor_index = input('Select a motor by entering its number: ');
    if motor_index > numel(Names) || motor_index < 1
        beep;
        fprintf('NO SUCH MOTOR NUMBER! Enter a number between 1 and %d.\n', numel(Names));
    end
end

mass = input('Enter the mass to be lifted (in kg): ');
height = input('Enter the height to lift the mass (in meters): ');
motor_name = Names(motor_index);
power = Specs(1, motor_index);
efficiency = Specs(2, motor_index);

% Calculate output power
efficiency_decimal = efficiency / 100;
output_power = efficiency_decimal * power;
g = 9.81;
energy_required = mass * g * height;
time = energy_required / output_power;
fprintf('Motor: %s\n', motor_name);
fprintf('Load lifted: %.2f kg\n', mass);
fprintf('Height lifted: %.2f meters\n', height);
fprintf('Time to lift the load: %.2f seconds\n', time);

%Task 2
mass = input('Enter the mass to be lifted by all motors (in kg): ');
height = input('Enter the height to lift the mass by all motors (in meters): ');
% Initialize results matrix
num_motors = length(Names);
results = zeros(5, num_motors);
% Calculate time for each motor
g = 9.81;  % Gravity constant
for k = 1:num_motors
    power = Specs(1, k);  % Power in watts
    efficiency = Specs(2, k);  % Efficiency in percentage
    efficiency_decimal = efficiency / 100;
    output_power = efficiency_decimal * power;
    % Energy required to lift mass
    energy_required = mass * g * height;
    % Time to lift
    time = energy_required / output_power;
    % Store results: power, efficiency, mass, height, time
    results(:, k) = [power; efficiency; mass; height; time];
end
% Export results to CSV file
csvwrite('Task2_Results.csv', results);
% Display the matrix to verify
disp('Results matrix:');
disp(results);
%Task 3
output_powers = Specs(1, :) .* (Specs(2, :) / 100);  % Output power for each motor
times = results(5, :);  % Time from the results matrix
scatter(output_powers, times, 'filled');
xlabel('Output Power (W)');
ylabel('Time to Lift Load (s)');
title('Motor Output Power vs. Time to Lift Load');
grid on;