Variables

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• Misc
  • Nick’s office hours start today
  • Math Learning Center open as of Monday (Jan. 26)
    • Hours roughly
      • Evenings Sunday - Thursday
      • Mid-morning through mid-afternoon Monday - Friday
  • Math colloquium
    • “Solutions to Polynomials in Two Variables”
    • Dr. Tom Tucker, UR math dept.
    • Thursday Jan 29th, 5:00 - 6:00 PM
    • Newton 204
    • Extra Credit (equivalent to up to 2 points on a lab) for going and writing a 1-paragraph summary
      • OK summary (1 point): what the main points were
      • Good summary (2 points): why you found it mathematically interesting
• Questions?
• Variables
  • Section 1.3
    • Setting variables equal to different numbers
    • Variables are changeable
      • So you can change a built-in function’s value
    • Variable-related commands
      • who, whos
    • Rules for variable names
      • Case-sensitive (a not same as A)
      • Pick names that make sense
      • Variable name = word not starting with digit
      • namelengthmax function to find out how long a name can be
        

        >> namelengthmax
        ans =
            63

    • Most basic way of using Matlab
    • Types?
      • Type aka class specifies what sort of data a variable can hold
      • Examples
        • Real numbers (double)
        • Imaginary too
          

          >> x = 3.14
          x =
              3.1400
          >> sqrt(-9)
          ans =
              0.0000 + 3.0000i

        • Integer
          • int8 = 8-bit integers
          • 1 bit can represent 2 values
          • 2 bits can represent 4 = 2² values
          • Generally, n bits can represent 2ⁿ values
          • 8 bits represents 2⁸ = 256 values
            • -128 to 127
              

              >> 2^8
              ans =
                  256

        • Truth values
        • Characters
  • Examples
    • Initialize, use, update
      

      >> x = 0
      x =
          0
      >> i = 1;
      >> i = i + 1
      i =
          2
      >> i = i + 1
      i =
          3
      >> x = 1;
      >> x = 2*x
      x =
          2

• Variables and Expressions Lab
  • Handout
• Next
  • Some counting and probability (as in lotteries)
  • Watch 3 videos
    • The Multiplication Principle at https://www.youtube.com/watch?v=sEul6TMYDY
    • Combinations at https://www.youtube.com/watch?v=uATuM3ajhBw&list=PL4098211B87018422&index=1
    • Expected Value at http://www.youtube.com/watch?v=DAjVAEDil_Q

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