1. Input and Output in MATLAB Lecture 13: Supporting Material Dr Kathryn Merrick Tuesday 14 th April, 2009

3. Overview Gathering user input Formatting output for display File input and output Code clichés for designing a user interface

4. An Introductory Problem… Question: At 200km/hr, what will stop in a shorter distance, a road car or a F1 race car?

5. From Problem to Program… 1.Understand the problem ‘in English’ 2.Develop a rough solution on paper 3.Implement the solution in MATLAB 4.Test your solution

6. Some Equations for Motion s is stopping distance u is initial velocity v is final velocity μ is the coefficient of friction between tyres and road g is gravity t is time a is acceleration

7. Demo 1: Interactive Calculator for Motion in MATLAB

8. Gathering User Input Numbers time = input('Enter time in seconds: '); Strings name = input('Enter your name: ', 's');

9. Displaying Simple Output disp('Error: You must enter a number from 1-3') disp('Now exiting the program... Goodbye.') disp(pi)

10. Demo 2: Formatting Output

11. Formatting Complex Output name = 'Kathryn'; office_number = 212; fprintf('The lecturer''s name is %s. Her office number is %u.\n', name, office_number);

12. Useful fprintf Options %s string %d decimal (scientific notation) %f floating point number %.2f floating point number to 2 decimal places \n new line \t tab

13. Quick Quiz: Code Clichés Name the two code clichés used in interactive calculator for motion: (1) Sentinel guarded loop (2) Enumeration

14. Demo 3: File I/O

15. File Input and Output Input [cartypes velocities] = textread(input_filename, '%s %f', 'delimiter', '\t'); Output open_output_file = fopen(output_filename, 'wt'); fprintf(open_output_file, '%s velocity is %f ms-1.\n', cartype, velocity); fclose(open_output_file);

16. Summary After today’s lecture you should be able to: Gather user input Format and display output Input and output data using files Design simple, text- based user interfaces