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MATLAB accepts log10 for common (base 10) logarithm. To find the log of 10, type in log10(10) and press enter, (ans = 1).

Practice the following examples to familiarize yourself with the common mathematical functions. Be sure to read the relevant help and doc pages for functions that are not self explanatory.

Calculate the following quantities:

  1. 2 3 3 2 1 ,
  2. 5 0.5 1
  3. 4 d 2 for d=2

MATLAB inputs and outputs are as follows:

  1. 2 3 3 2 1 is entered by typing 2^3/(3^2-1) (ans = 1)
  2. 5 0.5 1 is entered by typing sqrt(5)-1 (ans = 1.2361)
  3. 4 d 2 for d=2 is entered by typing pi/4*2^2 (ans = 3.1416)

Calculate the following exponential and logarithmic quantities:

  1. 2
  2. 5 10
  3. 10 5

MATLAB inputs and outputs are as follows:

  1. exp(2) (ans = 7.3891)
  2. log((5^10)) (ans = 16.0944)
  3. log10(10^5) (ans = 5)

Calculate the following trigonometric quantities:

  1. 6
  2. 45
  3. 45

MATLAB inputs and outputs are as follows:

  1. cos(pi/6) (ans = 0.8660)
  2. tan(45*pi/180) (ans = 1.0000)
  3. sin(pi)+cos(45*pi/180) (ans = 0.7071)

The format Function

The format function is used to control how the numeric values are displayed in the Command Window. The short format is set by default and the numerical results are displayed with 4 digits after the decimal point (see the examples above). The long format produces 15 digits after the decimal point.

Calculate θ 3 and display results in short and long formats.

The short format is set by default:

>>theta=tan(pi/3) theta =1.7321>>

And the long format is turned on by typing format long :

>>theta=tan(pi/3) theta =1.7321>>format long>>theta theta =1.732050807568877

Variables

In MATLAB, a named value is called a variable. MATLAB comes with several predefined variables. For example, the name pi refers to the mathematical quantity π, which is approximately pi ans = 3.1416

MATLAB is case-sensitive, which means it distinguishes between upper- and lowercase letters (e.g. data, DATA and DaTa are three different variables). Command and function names are also case-sensitive. Please note that when you use the command-line help, function names are given in upper-case letters (e.g., CLEAR) only to emphasize them. Do not use upper-case letters when running functions and commands.

Declaring variables

Variables in MATLAB are generally represented as matrix quantities. Scalars and vectors are special cases of matrices having size 1x1 (scalar), 1xn (row vector) or nx1 (column vector).

Declaration of a scalar

The term scalar as used in linear algebra refers to a real number. Assignment of scalars in MATLAB is easy, type in the variable name followed by = symbol and a number:

a = 1

Example1
Assignment of a scalar quantity.

Declaration of a row vector

Elements of a row vector are separated with blanks or commas.

Let's type the following at the command prompt:

b = [1 2 3 4 5]

Example2
Assignment of a row vector quantity.

We can also use the New Variable button to assign a row vector. In the tool strip, select Home>New Variable. This action will create a variable called unnamed which is displayed in the workspace. By clicking on the title unnamed, we can rename it to something more descriptive. By double-clicking on the variable, we can open the Variable Editor and type in the values into spreadsheet looking table.

Example_2a1
Using the New Variable button in the tool strip.
Example2a
Assignment of a row vector by using the Variable Editor.

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Source:  OpenStax, A brief introduction to engineering computation with matlab. OpenStax CNX. Nov 17, 2015 Download for free at http://legacy.cnx.org/content/col11371/1.11
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