# 4.11: Common Vector Functions

• • Carey Smith
• Oxnard College
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By Carey A. Smith

##### Example $$\PageIndex{1}$$ Functions that compute a single number from a vector

% This is vector of CO2 levels (ppm) measured at Mauna Loa Hawaii in 2018: CO2 = [407.96, 408.32, 409.39, 410.25, 411.24, 410.79, 408.70, 406.97, 405.52, 406.00, 408.02, 409.08]; % Reduce functions: CO2_sum = sum(CO2) % Total CO2_length = length(CO2) % The number of items in the vector CO2_min = min(CO2) % Minimum CO2_max = max(CO2) % Maximum
Solution

N/A

##### Example $$\PageIndex{1}$$ Functions that apply an operation to a vector

This is vector of CO2 levels (ppm) measured at Mauna Loa Hawaii in 2018:
CO2 = [407.96, 408.32, 409.39, 410.25, 411.24, 410.79, 408.70, 406.97, 405.52, 406.00, 408.02, 409.08]; % Apply functions and operators: CO2_sqrt = sqrt(CO2) % Square roots of the elements CO2_square = CO2.^2 % Squares of the elements (element-wise) CO2_log10 = log10(CO2) % logarithm, base 10 CO2_log = log(CO2) % logarithm, base e (natural logarithm) % log() should be ln(), but this is a long tradition in programming languages. CO2_exp = exp(CO2) % e^x 

CO2_column=CO2' % The ' symbol transposes a vector

Note that sin(theta), cos(theta), tan(theta) are for theta in radians.

theta = pi*(0 : 0.1 : 0.3) theta_sin = sin(theta) theta_cos = cos(theta) theta_tan = tan(theta)

Note that sind(alpha), cosd(alpha), tand(alpha) are for alpha in degrees.

alpha = 0 : 15 : 45 sin_alpha = sind(alpha) cos_alpha = cosd(alpha) tan_alpha = tand(alpha)

The attached file, MatlabCommands_Brian_Vick.pdf, courtesy of Dr. Brian Vick from Virginia Tech, is a very useful summary of the the most common MATLAB commands.

Solution

##### Exercise $$\PageIndex{1}$$ Squareroot of the sum of squares

Create this vector: v = [3, 4, 5, 6, 7]

Then write 1 line of cose that computes the square root of the sum of the squares of the elements of the vector, without using a loop.Write 1 line of code that

Use the vector operator v.^2 to square each element of the vector; sum the elements sum(); compute the squareroot.

##### Exercise $$\PageIndex{1}$$ sin() of a vector

(1 pt) Create a Matlab script: sin_vector_YourName.m
(1 pt) Clear any variables; close any figures; eliminate white space; clear the console with this line of code:
clear all; close all; format compact; clc;

%% Part 1
(1 pt) Create a vector called degrees = 0 to 90 in steps of 10 degrees
degrees = 0 : 10 : 90;

(2 pts) Use sind() to compute the sines of the degrees vector.

(2 pts) Create a 2nd vector: radians = (2*pi/360)*degrees.
(2 pts) Use sin() to compute the sines of the radians vector.
%% Part 2
(2 pts) Convert the radians vector created in part 1 from a row vector
to a column vector with this code:
(1 pt) Use cos() to compute the cosine this column radians vector.

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