Difference between revisions of "EGR 103/Fall 2013/Lab 3"

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Revision as of 18:20, 8 September 2014

Concepts discussed during explanation of each problem:

  • First problem: Van Der Waals Equation
    • Use of strings in MATLAB
      • Numerical values stored for letters
      • Issue with strings of differing lengths
    • strcmp command
    • Use of switch...case statement instead of if tree with strcmp
      • otherwise case
      • multiple triggers with {'trigger1', 'trigger2', ... }
      • Only good for exact matches
    • Plotting using different point styles
  • Second problem: Beam Displacement
    • if statements and logic
      • implied all() with logic
    • MATLAB:Logical Masks
      • Be careful about (logic) .* (function) versus logic .* function
        • 2<1*3 yields "true"
      • Never use a<X<b; use a<X & X<b instead
        • a<X\(<\)b yields all 1's if b>1, regardless of a or X values
    • find command
      • Finding non-zeroes
        • find(X)
        • find(A>0)
      • Using indices to determine values
        • X(find(X)), A(find(A>0)), t(find(y==min(y)))
    • Using more points for better answer
    • MATLAB tolerance and dangers of ==
      • min(y)==-1 fails
      • format long e shows why
      • use abs(min(y)-(-1)) < tol instead for some value of tol
    • Speed of displaying versus creating matrices
    • Problems using huge number of points for plot
  • Third problem: Pipe
    • Notion that functions can do more than just calculate matrices
  • Fourth problem: Leap year
    • Notion of validating inputs
    • Using nargin to check input count along with if tree
    • error command
    • Use of testing function to create diary
  • Fifth problem: Rocket
    • Use of anonymous function with logical mask