This document discusses how to analyze programs for efficiency. It explains that programs should be analyzed both before and after implementation to estimate things like computation time and storage requirements. Key aspects to consider include the number of times loops and statements will be executed, how algorithms and data structures are implemented, and how the program's performance compares to alternatives. An example program for computing the nth Fibonacci number is provided to illustrate some of these concepts.

1. How to Create Programs

5. procedure binsrch (a: elementlist; x: element; var n,j: integer ); {search the sorted array a[1..n] for x} initialize lower and upper begin while there are more elements do begin let a[mid] be the middle element; case compare (x, a[mid]) of '>': set lower to mid + 1; '<': set upper to mid - 1; '=': found x; end ; {of case } end ; {of while } not found; end ;{of binsrch}

6. How to Analyze Programs

9. To clarify some of the ideas stated in this section, take a look at a simple program for computing the n-th Fibonacci number. The Fibonacci sequence starts as 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55,.... Each new term is obtained by taking the sum of the two previous terms. If we call the first term of the sequence F[0] then F[0]=0, F[1]=1 and in general F[n] = F[n-1] + F [n-2], n>=2.