ENGR 1181 | MATLAB 5: Array Operations
Classroom Guide

ENGR 1181 | MATLAB 5: Array Operations

Classroom Guide

Learning Objectives

1.  Explain the meaning of element-by-element operations.

2.  Identify situations where the standard operators in MATLAB (when used with arrays) are reserved for linear algebra, which is not always element-by-element.

3.  Apply dot operators for the cases where linear algebra is not element-by-element and therefore dot operators are needed to produce element-by-element calculations.

4.  Apply built-in functions for analyzing arrays.

Textbook Reading

Chapter 3.4 – 3.8

Topics

This class contains the following topics:

1.  Review of Scalar Math

2.  Scalar-Vector Math

3.  Vector-Vector Math

4.  Built-in Array Functions

Outline

Below is an outline of the topics and the order in which they should be covered:

1.  Review of Scalar Math

  1. MATLAB has scalar math operations
  2. Use MATLAB like a calculator for basic mathematical operations: addition, subtraction, multiplication, division, etc.

2.  Scalar-Vector Math (Classroom Activity – Example 1, Example 2)

  1. Show examples of scalar-vector addition/subtraction

i.  MATLAB computes element-by-element as default

ii. No “dot” operator needed

  1. Show examples of scalar-vector multiplication/division

i.  MATLAB computes element-by-element as default for multiplication

ii. No “dot” operator needed for scalar-vector multiplication

iii.  Division works without a “dot” operator ONLY when the scalar is to the right of the division sign.

3.  Vector-Vector Math (Classroom Activity – Examples 3, 4 & 5)

  1. Show examples of vector-vector addition/subtraction

i.  No “dot” operator needed. Default is element-by-element

ii. Vectors used in computation must be of the same length.

  1. Show examples of vector-vector multiplication/division

i.  Without the “dot” operator, MATLAB solves calculations with arrays following the rules of linear algebra. We won’t be doing linear algebra in this class so we need to run element-by-element computations.

ii. When multiplying or dividing two arrays, include the “dot” operator BEFORE the mathematical symbol.

  1. Show examples of exponential calculations

i.  Exponents are not actually scalar operations. They are operations involving the product of the same vector.

ii. Include the “dot” operator BEFORE the mathematical symbol. This is true when raising a vector to a scalar or to another vector.

4.  Built-in Array Functions (Classroom Activity – Example 6)

  1. MATLAB has many built-in functions for analyzing arrays and matrices. For example:

i.  mean()

ii. sum()

iii.  sort()

iv.  median()

v. std()

vi.  max()

5.  Prompt: Remember what is DR PIE?

6.  Students will complete Part 1 of the assignment to turn in by the end of class. Once finished, students may start on Part 2 due by the next class. Students will submit Part 1 of the assignment to the Carmen dropbox as a PDF.

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