MATLAB Data Types & Plotting: Complex Numbers, Strings, Arrays, Plots, Slides of Computer Science

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Chapter 6 Additional Data

Types and plot Types

Chun-Ming Tsai

Contents

• Complex data
• String functions
• Multidimensional Arrays
• Additional Data Types
• Additional Two-Dimensional Plots
• Three-Dimensional Plots

6.1 Complex Data

• Complex numbers are numbers with both a real and an

imaginary component.

P

a + bi

real axis

imaginary axis

b

a

P a + bi

real axis

imaginary axis

z



a

b

z a b

b z

a z

c a bi z

1

2 2

tan

sin

cos

= −

= +

=

=

= + = 









• If complex numbers c 1 and c 2 are defined as c 1 = a 1 + b 1 i ,

and c 2 = a 2 + b 2 i , then the addition, subtraction, multiplication, and division of c 1 and c 2 are defined as:

i a b

b a a b

a b

a a bb

c

c

c c a a bb a b b a i

c c a a b b i

c c a a b b i

2 2

2 2

1 2 1 2 2 2

2 2

1 2 1 2

2

1

1 2 1 2 1 2 1 2 1 2

1 2 1 2 1 2

1 2 1 2 1 2

• Using complex numbers with relational

operators

• It is possible to compare two complex numbers with the == relational operator - To see if they equal to each other.
• To compare them with the ~= operator
  • To see if they are not equal to each other.
• However, comparisons with the >, <, >=, or <= operators do not produce the expected results. - Compare with real parts

• Compare with the magnitudes of c 1 and c

See Table 6.1 (page 266)

• Example 6.1 The Quadratic Equation

(revisited)

• Page 270

• If both the real and imaginary parts of the

function are of interest, then the user has

several choices.

• Alternatively, the real part of the function

can be plotted versus the imaginary part.