While Loops with Input and Output

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• Misc
  • Colloquium room change: now Newton 204
  • First hour exam
    • Sample exam from last semester available on “Exercises” page
    • Friday (Oct. 23)
    • Material from start of semester through matrices (e.g., arithmetic, scripts & functions, vectors, plotting, matrices, etc.)
    • 3 - 5 short-answer questions
    • Precise Matlab syntax will only matter at the “what I expect” vs “perfect” level
    • Full class period
    • Open book, notes, computer; closed person
• Questions?
• While Loops with Input and Output
  • Guessing game - read numbers from user until they enter the right one
  • Matlab input and output commands
    • input
      

      >> input( 'Enter a number ' )
      Enter a number 765
      ans =
         765
      >> input( 'Enter a number ' )
      Enter a number 3 + sqrt(17)
      ans =
          7.1231

    • fprintf
      

      >> x = 3.7
      x =
          3.7000
      >> fprintf( 'Widgets cost %f today\n', x )
      Widgets cost 3.700000 today
      >> fprintf( 'Widgets cost %f today and %f yesterday\n', x, x-5 )
      Widgets cost 3.700000 today and -1.300000 yesterday
      >> fprintf( 'Widgets cost %5.2f today and %0.2f yesterday\n', x, x-5 )
      Widgets cost  3.70 today and -1.30 yesterday
      >> x = 10379
      x =
             10379
      >> fprintf( 'Widgets cost %5.2f today and %0.2f yesterday\n', x, x-5 )
      Widgets cost 10379.00 today and 10374.00 yesterday

  • Guessing game algorithm, version 1
    

    program creates random number between 0 and 50
    user guesses number
    if guess matches created number, stop
    otherwise get user guess again

  • Version 2
    

    n = random number between 1 and 50
    a = user input
    while a ≠ n
        print “you’re wrong” message
        a = user input

  • Final Matlab script
    

    %{ n = random number between 1 and 50
       a = user input
       while a ≠ n
          print “you’re wrong” message
          a = user input
    %}
    n = randi( 3, 1 );
    a = input( 'Guess a number ' );
    while ( a ~= n )
        fprintf( 'Error, try again\n' );
        a = input( 'Guess a number ' );
    end

• Next
  • Logical Operators
    • Section 13.3
  • Newton’s Method
    • Watch (required) “Newton’s Method” video at https://www.youtube.com/watch?v=WO0GMNUCMNw
      • Or at https://cloud.ensemblevideo.com/Playlist/t3FQq8b6

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