• Midterm Exam: Grade Distribution
  • 2: 1 - 70
  • 10: 70 - 79
  • 28: 80 - 89
  • 43: 90 - 99
  • 69: 100 - 110
  • 98: 111 - 120
• See me after class if you missed the midterm
• Quiz Wednesday

• load
• find
• printall
• compare

• output counts rather than displaying data
• logical expressions
• for numeric data give ranges

• Example: Personnel Database
• Employees
• Departments
• Job Descriptions

• zero an array
• initialize to other value
• count the number of negative numbers in an array
• sum an array
• read in array
• print an array

• give the first/last letter in a string
• remove the first/last letter in a string
• count the number of 'e's in a string
• reverse letters in a string

• Procedure invokes itself

• decomposing problem
• base case
• recursive case which gets closer to solution
• Factorial
  • n! = n * (n-1)!
  • 0! = 1

• Raw multiplications
  • X^N = X * X * X * ... * X
  • N-1 multiplications
• Save work; clump things together
  • SX = X * X
  • X^N = SX * SX * ... * SX
  • roughly N/2 times ...
• Refine this latter approach

• Base case: X^0 = 1.0
• N is even case: X^N = X^(N/2) * X^(N/2)
• N is odd case: X^N = X * X^(N/2) * X^(N/2)

Any nontrivial computer language that one can invent is apparently capable of computing no more and no fewer functions that all the other nontrivial programming languages.

This part of Pascal lets you solve all kinds of algorithms