Matlab hold on

Introduction to Matlab hold on

The following article provides an outline for Matlab hold on. Matlab’s ‘hold’ command determines whether the newly created graphic object will be added to the existing graph or will it replace the existing objects in our graph. The command ‘hold on’ is used to retain our current plot & its axes properties in order to add subsequent graphic commands to our existing graph.

For example, we can add 2 trigonometric waves, sine and cos, to the same graph using the hold on command.

Syntax:

• Command ‘hold on’ is used to retain the plot in current axes. By doing so, the new plot is added to the existing axes without making any changes to the existing plot.
• Command ‘hold off’ is used to change the hold on state back to off.

Examples of Matlab hold on

Let us see how to add a new plot to the existing axes in Matlab using the ‘hold on’ command.

Example #1

In this example, we will use the ‘hold on’ command to add 2 plots to a single graph. We will plot 2 different logarithmic functions in one graph for our 1^st example.

The steps to be followed for this example are:

• Initialize the 1^st function to be plotted.
• Use the plot method to display the 1^st function.
• Use the ‘hold on’ command to ensure that the plot of the next function is added to this existing graph.
• Initialize the 2^nd function to be plotted.
• Use the plot method to display the 2^nd function.
• Use the ‘hold off’ command to ensure that the next plot, if any, is added as a new graph.

Code:

x = linspace (0, 5);

y = log (5* x);

[Initializing the 1^st logarithmic function]

plot (x, y)

[Using the plot method to display the figure]

hold on

x = linspace (0, 5);

z = log (3 * x);

[Initializing the 2^nd logarithmic function]

plot(x, z)

[Using the plot method to display the figure]

hold off

[Using the ‘hold off’ command to ensure that the next plot, if any, is added as a new graph]

This is how our input and output will look like in the Matlab command window.

Input:

Output:

As we can see in the output, we have obtained 2 logarithmic functions in the same graph as expected by us.

Example #2

In this example, we will use the ‘hold on’ command to add 2 different exponential functions in one graph.

The steps to be followed for this example are:

• Initialize the 1^st function to be plotted.
• Use the plot method to display the 1^st function.
• Use the ‘hold on’ command to ensure that the plot of the next function is added to this existing graph.
• Initialize the 2^nd function to be plotted.
• Use the plot method to display the 2^nd function.
• Use the ‘hold off’ command to ensure that the next plot, if any, is added as a new graph.

Code:

x = linspace(0, 5);

y = exp(2* x);

[Initializing 1st exponential function]

plot(x, y)

[Using the plot method to display the figure]

hold on

x = linspace(0, 5);

z = exp(2.1 * x);

[Initializing 2^nd exponential function]

plot(x, z)

[Using the plot method to display the figure]

hold off

[Using the ‘hold off’ command to ensure that the next plot, if any, is added as a new graph]

This is how our input and output will look like in the Matlab command window.

Input:

Output:

As we can see in the output, we have obtained 2 exponential functions in the same graph as expected by us.

In the above 2 examples, we saw how to add 2 functions to a single graph. We can also use the same ‘hold on’ command to add more than 2 functions also. Next, we will see how to add 3 functions to the same graph.

Example #3

In this example, we will use the ‘hold on’ command to add 3 plots to a single graph. We will plot 3 different exponential functions in one graph for this example.

The steps to be followed for this example are:

• Initialize the 1^st function to be plotted.
• Use the plot method to display the 1^st function.
• Use the ‘hold on’ command to ensure that the next plot is added to this existing graph.
• Initialize the 2^nd function to be plotted.
• Use the plot method to display the 2^nd function.
• Use the ‘hold on’ command to ensure that the next plot is added to this existing graph.
• Initialize the 3^rd function to be plotted.
• Use the plot method to display the 3^rd function.
• Use the ‘hold off’ command to ensure that the next plot, if any, is added as a new graph.

Code:

x = linspace(0, 5);

y = exp(2* x);

[Initializing 1st exponential function]

plot(x, y)

[Using the plot method to display the figure]

hold on

x = linspace(0, 5);

z = exp(2.1 * x);

[Initializing 2^nd exponential function]

plot(x, z)

[Using the plot method to display the figure]

hold on

x = linspace(0, 5);

a = exp(2.2 * x);

[Initializing 3^rd exponential function]

plot(x, a)

[Using the plot method to display the figure]

hold off

[Using the ‘hold off’ command to ensure that the next plot, if any, is added as a new graph]

This is how our input and output will look like in the Matlab command window:

Input:

Output:

As we can see in the output, we have obtained 3 exponential functions in the same graph as expected by us.

Conclusion

Matlab’s ‘hold on’ command is used to add more than 1 graphic object to the same figure. This command is used to retain our current plot & its axes properties in order to add subsequent graphic commands to our existing graph.

Recommended Articles

This is a guide to Matlab hold on. Here we discuss the introduction to Matlab hold on along with examples for better understanding. You may also have a look at the following articles to learn more –

1. Laplace Transform MATLAB
2. Matlab Global Variables
3. Matlab plot title
4. Matlab Index Exceeds Matrix Dimensions