Types of Analysis

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This lecture introduces the two main types of algorithm analysis: experimental (a posteriori) and theoretical (a priori). The instructor first defines experimental or relative analysis as evaluating an algorithm after it has been converted to code. Its advantage is that it provides exact values with no rough estimates, but its disadvantage is that the final result depends on many factors beyond the algorithm itself, such as background software, hardware, programming language, and even room temperature. The lesson then transitions to a priori analysis, also called independent or absolute analysis, which evaluates only the algorithm using asymptotic notations and mathematical tools. In this approach, performance is determined in terms of input size rather than actual execution time. The instructor writes example functions f1(n) = n^2 + 2n + 5 and f2(n) = n^3 to illustrate comparing growth rates. Finally, the concept of order of magnitude is defined as the number of times fundamental operations are involved in a statement, determined through a two-step process: finding the number of fundamental operations and then determining how many times they execute.

Chapters

1. 0:00 – 2:00 00:00-02:00

   The slide titled 'Types of Analysis' presents the first type, 'Experimental or Apostrium or relative analysis,' defined as analyzing an algorithm after it is converted to code. Red underlines are added progressively to key phrases, including the definition and the advantage line 'Exact values no rough.' The disadvantage section notes that results depend on many factors such as background software, hardware, programming language, and even the temperature of the room. The instructor gestures while explaining these points.

2. 2:00 – 4:36 02:00-04:36

   The slide transitions to 'Apriori Analysis or Independent analysis or Absolute analysis,' which uses asymptotic notations and mathematical tools to evaluate only the algorithm in terms of input size. The instructor writes f1(n) = n^2 + 2n + 5 and f2(n) = n^3 to illustrate comparing functions. A new slide then states 'Asymptotic Analysis is not perfect' with advantage and disadvantage lines. The final slide defines 'Order of magnitude' as the number of times fundamental operations are involved in a statement, broken into two steps: finding the number of fundamental operations and determining how many times they execute.

The lecture progresses from practical to theoretical analysis. Experimental (a posteriori) analysis measures actual running times after coding, yielding exact values but being affected by external factors like hardware and software. A priori (independent) analysis is purely mathematical, using asymptotic notation to determine the order of magnitude based on input size. The example functions f1(n) and f2(n) demonstrate how polynomial terms are compared to assess growth. The order of magnitude concept is operationalized as a two-step counting process for fundamental operations, providing the foundation for asymptotic analysis.