3.5.1: Create a 2D x-y Sine-Wave Plot with a for Loop
- Page ID
- 84378
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)By Carey A. Smith
2-Dimensional plots of a time sequence can be easily created in MATLAB and in Octave.
Octave needs a graphics toolkit to plot graph. Insert this line in your code before creating your first figure:
graphics_toolkit("qt") % Do not use with MATLAB
If that doen't work, try this version:
graphics_toolkit("fltk")
The graphics toolkit is only for Octave. It is not needed for MATLAB and will cause an error if attempted.
For more information on graphics toolkit options, see:
https://docs.octave.org/interpreter/Graphics-Toolkits.html
The key lines of code for creating a plot in both MATLAB and Octave are:
figure; % Open a figure window. The plot is created in this figure window.plot(t, sin_t, 'o')- The first variable, t, is the x coordinate of the point.
- The second variable, sin_t, is the y coordinate of the point.
- The 'o' means to use a circle for point's marker.
hold on; % Let additional points be plotted on the same figure
It can be useful to code this example together as a class.
% Compute and plot points of a sine wave
% using a script with a "for loop"
clear all; % Clear all variables
clc; % Clear the console (computer screen)
close all; % close all figures
format compact; % Don't insert blank lines on the console
graphics_toolkit("fltk") % Include this line when using Octave. Not for Matlab.
%% Initialize variables
period = 0.5; % seconds
t_end = 3*period; % The end of the interval
dt = period/16; % time between points
%%
figure; % Open a figure window
xlim([0,t_end]) % Set the x-axis to be 0 to t_end
ylim([-1,1]) % Set the x-axis to be -1 to 1
grid on; % Draw grid lines
hold on; % Let additional points be plotted on the same figure
%%
for t = 0 : dt : t_end % t = 0, dt, 2*dt, ... t_end
% Compute the sine for the current value of t
sin_t = sin(2*pi*t/period);
plot(t, sin_t, 'o')
pause(0.3) % pause long enuf to see each point as it is plotted
end
Solution
