Drawing Multiple Functions on the Same Graph

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You can draw multiple graphs on the same plot. The following example demonstrates the concept −

Example

Create a script file and type the following code −

x = [0 : 0.01: 10];
y = sin(x);
g = cos(x);
plot(x, y, x, g, '.-'), legend('Sin(x)', 'Cos(x)')

MATLAB generates the following graph −

Setting Colors on Graph

MATLAB provides eight basic color options for drawing graphs. The following table shows the colors and their codes −

Code	Color
w	White
k	Black
b	Blue
r	Red
c	Cyan
g	Green
m	Magenta
y	Yellow

Example

Let us draw the graph of two polynomials

• f(x) = 3x⁴ + 2x³+ 7x² + 2x + 9 and
• g(x) = 5x³ + 9x + 2

Create a script file and type the following code −

x = [-10 : 0.01: 10];
y = 3*x.^4 + 2 * x.^3 + 7 * x.^2 + 2 * x + 9;
g = 5 * x.^3 + 9 * x + 2;
plot(x, y, 'r', x, g, 'g')

When you run the file, MATLAB generates the following graph −

Setting Axis Scales

The axis command allows you to set the axis scales. You can provide minimum and maximum values for x and y axes using the axis command in the following way:

axis ( [xmin xmax ymin ymax] )

The following example shows this −

Example

Create a script file and type the following code −

x = [0 : 0.01: 10];
y = exp(-x).* sin(2*x + 3);
plot(x, y), axis([0 10 -1 1])

When you run the file, MATLAB generates the following graph −

Generating Sub-Plots

When you create an array of plots in the same figure, each of these plots is called a subplot. The subplot command is used for creating subplots.

Syntax for the command is −

subplot(m, n, p)

where, m and n are the number of rows and columns of the plot array and pspecifies where to put a particular plot.

Each plot created with the subplot command can have its own characteristics. Following example demonstrates the concept −

Example

Let us generate two plots −

y = e^−1.5xsin(10x)

y = e^−2xsin(10x)

Create a script file and type the following code −

x = [0:0.01:5];
y = exp(-1.5*x).*sin(10*x);
subplot(1,2,1)
plot(x,y), xlabel('x'),ylabel('exp(–1.5x)*sin(10x)'),axis([0 5 -1 1])
y = exp(-2*x).*sin(10*x);
subplot(1,2,2)
plot(x,y),xlabel('x'),ylabel('exp(–2x)*sin(10x)'),axis([0 5 -1 1])

When you run the file, MATLAB generates the following graph −

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