CSI 101 Elements of Computing Spring 2009 Lecture #1 – From Math to Computers Wednesday, January 21, 2009

Similarities to Math  Use of variables  Most of what you detail in programs are general  Variables represent values  Based on data  All functions and operations work with variables and data values

Level of Programming  Detailed, specific steps  Get down to level of one data value interacting with another  Think about how you are getting the data  Consider what you are doing with the data

Example  Find the largest of three numbers  Can only use less than or greater than  That comparison checks only two numbers  Thus, compare two of them, then compare the largest to the third

Math in Programs  Most programming languages use same mathematical operators as traditional math  Arithmetic : +, -, /  Multiplication is * instead of x  Equate: =  Comparison:, =  No symbol for root  Exponentiation uses different symbols

Arithmetic Example  Always remember that, in computers, the answer to a calculation is ALWAYS on the left side of the equation  It’s the variable you are placing the value into  In traditional math, it doesn’t matter which side Ans = A + 3*B

Order of Operations  Computers use the same order of operations as math 1.Parentheses 2.Exponentiation 3.Multiplication and Division 4.Addition and Subtraction

PEMDAS Example Ans = A + 3*B / 4 does not have the same answer as Ans = (A + 3*B)/4