nix

    開始念Algorithm了，依照慣例，為了要釐清自己的觀念和讓自己複習及查資料方便，還是在念書的時候盡量整理筆記。Algorithm也是一門非常耐人尋味的學問呢...

1.        The Role of Algorithms in Computing

• The theoretical study of computer-program performance and resource usage.
• An algorithm is any well-defined computational procedure that takes some value, or set of values, as input and produces some value, or set of values, as output. An algorithm is thus a sequence of computational steps that transform the input into the output.
• The theoretical study of computer-program performance and resource usage.
  • Algorithms help us to understand scalability.
  • Performance often draws the line between what is feasible and what is impossible.
  • Algorithmic mathematics provides a language for talking about program behavior.
  • The lessons of program performance generalize to other computing resources.
  • Speed is fun!
    
• In general, an instance of a problem consists of the input (satisfying whatever constraints are imposed in the problem statement) needed to compute a solution to the problem.
• Which algorithm is best for a given application depends on-among other factors-
  • (1)the number of items to be sorted,
    
  • (2)the extent to which the items are already somewhat sorted, 
  • (3)possible restrictions on the item values, and 
  • (4)the kind of storage device to be used: main memory, disks, or tapes.
• An algorithm is said to be correct if, for every input instance, it halts with the correct output.