Matlab Graphics

Matlab Graphics

Visualization and Plotting

2D PlottingGiven the arrays x = [0 1 2 3] and y = [0 1 4 9], use the plot function toproduce a plot of x versus y.

Matlab Code

>> x=[0 1 2 3];

>> y=[0 1 4 9];

>> plot(x,y)

Output

Make a plot of the function f (x) = x2 for −5 ≤ x ≤ 5Matlab Code

>> x=linspace(-5,5,100);

>> plot(x,x.^2)

Output

Symbol Descriptionb blueg greenr redc cyanm magentay yellowk blackw white. pointo circlex x-mark+ plus* star

s squared diamondv triangle (down)ˆ triangle (up)< triangle (left)> triangle (right)p pentagramh hexagram- solid: dotted-. dashdot- - dashed(none) no line

Make a plot of the function f (x) = x2 for −5 ≤ x ≤ 5 using a dashed green lineMatlab Code>> x=linspace(-5,5,100);

>> plot(x,x.^2,'g--')

Output

Make a plot of the function f (x) = x2 and g(x) = x3 for −5 ≤ x ≤ 5 Use different colors and markers for each functionM -File Code%Matlab Graphics 1 x=linspace(-5,5,20);hold onplot(x,x.^2,'ko');plot(x,x.^3,'r*');hold off

Output

Add a title and axis labels to the previous plot

M-File Codex=linspace(-5,5,20);hold onplot(x,x.^2,'ko');plot(x,x.^3,'r*');hold offtitle('Plot of Various Poynmials')xlabel('x')ylabel('y')

Output

Use the sprintf function to change the title of the previous plot to “Plot of VariousPolynomials from −5 to 5"

M - File Codex=linspace(-5,5,20)hold onplot(x,x.^2,'ko')plot(x,x.^3,'r*')

hold offtitle(sprintf('Plot of various polynomials for %d to %d',x(1), x(end)))xlabel('xaxis')ylabel('yaxis')grid on

OutPut

Add a legend to the previous plot using the legend function

M-File Codex=linspace(-5,5,20)hold onplot(x,x.^2,'ko')plot(x,x.^3,'r*')hold offtitle(sprintf('Plot of various polynomials for %d to %d',x(1), x(end)))xlabel('xaxis')ylabel('yaxis')legend('quadratic','cubic')

Output

Use the axis function to change the limits such that x is visible from −6 to 6 and y is visible from −10 to 10

M-Filex=linspace(-5,5,100)hold onplot(x,x.^2,'ko')plot(x,x.^3,'r*')hold offtitle(sprintf('Plot of various polynomials for %d to %d',x(1), x(end)))xlabel('xaxis')ylabel('yaxis')legend('quadratic','cubic')axis([-6 6 -10 10])grid on

OutPut

Given the arraysx = [0 1 2 3 4 5]andy = [1 2 4 8 16 2], create a 2×3subplot where each subplot plots x versus y using plot, scatter, bar, loglog, semilogx,and semilogy. Title and label each plot appropriately. Use a grid, but a legend is not necessary.

M-File Code

x=[0 1 2 3 4 5];y=[1 2 4 8 16 2]; subplot(2,3,1)plot(x,y)title('Plot')xlabel('X')ylabel('Y')grid on subplot(2,3,2)scatter(x,y)title('scatter')xlabel('X')ylabel('Y')

grid on subplot(2,3,3)bar(x,y)title('Bar')xlabel('X')ylabel('Y')grid on subplot(2,3,4)loglog(x,y)title('LogLog')xlabel('X')ylabel('Y')grid on subplot(2,3,5)semilogx(x,y)title('Semilogx')xlabel('X')ylabel('Y')grid on subplot(2,3,6)semilogy(x,y)title('semilogy')xlabel('x')ylabel('y')grid on

OutPut

3D Plotting

M-File Codet=[0:pi/50:10*pi];plot3(sin(t),cos(t),t)grid onaxis squaretitle('Parametric curve')xlabel('x')ylabel('y')zlabel('t')

OutPut

Make a 1 × 2 subplot of the surface f (x, y) = sin (x) ・ cos (y) for −5 ≤ x ≤ 5,−5 ≤y ≤ 5, the first using the surf function and the second using the contour function. Take care touse a sufficiently fine discretization in x and y to make the plot look smooth.

M-File Code

x=-5:.2:5;y=-5:.2:5;[X,Y]=meshgrid(x,y);z=sin(X).*cos(Y);subplot(1,2,1)surf(x,y,z)title('Surface plot using Surf')xlabel('x')ylabel('y')zlabel('z')subplot('1,2,2')contour(x,y,z)title('Surface plot using contour')xlabel('x')ylabel('y')

OutPut

Fplot

f(t)= e−2t sin t for 0 ≤ t ≤ 4,

Command Window code

>> fplot('exp(-2*t)*sin(t)',[0,4]),xlabel('t'),ylabel('f(t)'),title('Damped Spring Forcing')

Plotting Discrete DataNow let’s touch on some practical uses of MATLAB that you might need at workor in the field. First let’s see how we can use plot(x, y) to plot a discrete set of datapoints and connect them with a line. Let’s say we have a class with five students:Adrian, Jim, Joe, Sally, and Sue. They took an exam and received scores of 50, 98,75, 80, and 98, respectively. How can we plot this data?

1.Bar PlotM file Code>> x=[1:5];>> y=[50,98,75,80,98];>> bar(x,y),xlabel('student'),ylabel('score')>> bar(x,y),xlabel('student'),ylabel('score');>> bar(x,y),xlabel('student'),ylabel('score'),title('Final Exam')

OutPut

2.Stem Plot

M-File Code>> t=[0:5:200];>> f=exp(-0.01*t).*sin(t/4);>> stem(t,f),xlabel('time(sec)'),ylabel('spring response');

OutPut

Polar Plot

command window

>> a=2;>> theta=[0:pi/20:2*pi];>> r=a*theta;>> polar(theta,r)

Out Put

2.polar plot

Command window

a=2;>> theta=[0:pi/90:2*pi];>> >> r=1+2*cos(theta);

Output

Contour Plot

Command Window

>> [x,y]=meshgrid(-5:0.1:5,-3:0.1:3);>> z=x.^2+y.^2;>> contour(x,y,z)

Output

Contour 3d plot

Command Window>> [x,y]=meshgrid(-5:0.1:5,-3:0.1:3);>> z=x.^2+y.^2;>> contour3(x,y,z)

output

Contour 3d plot

Command Window

>> [x,y]=meshgrid(-5:0.1:5,-3:0.1:3);>> z=cos(x).*sin(y);>> contour3(x,y,z)>>

Difference between plot,semilogx,semilogy

1.plot

Command Window>> x=0:0.2:100;>> y=x.^2;>> plot(x,y

Out Put

2.semilogx

Command Window

>> x=0:0.2:100;>> y=x.^2;

OutPut

3. semilogy

command window

>> x=0:0.2:100;>> y=x.^2;>> semilogy(x,y)

output

4.loglog

Command Window

>> x=0:0.2:100;>> y=x.^2;

output

Plotting of different arbitrary points

>> plot([0,1],[4,3],[2,0],[5,-2])

output

New Command

gtextcommand window >> x=[0:0.1:10];>> y=x.^3+x.^2+3.*x;>> plot(x,y),xlabel('X'),ylabel('Y'),title(' gtext comand checking'),legend('x.^3+x.^2+3.*x'),gtext('pakistan')

output