MATLAB 2D Semilogx()

The MATLAB function semilogx() is used to create a 2D plot with logarithmic scaling along the x-axis. This is useful for visualizing data that varies over a large range of values, where a linear scale would result in a crowded or unreadable plot. The function works by taking the logarithm of the x-axis values before plotting them, while leaving the y-axis values unchanged.

Syntax

The basic syntax of the semilogx() function is as follows:

semilogx(X, Y)

where X and Y are the x and y-coordinate data, respectively.

Example

Consider the following dataset of values from 1 to 1000:

x = 1:1000;
y = sin(x);

Plotting this data with a linear axis using plot() results in a crowded plot:

plot(x, y)
xlabel('X')
ylabel('Y')
title('Linear Scale')

However, using semilogx() with a logarithmic axis for X produces a clearer plot:

semilogx(x, y)
xlabel('X')
ylabel('Y')
title('Logarithmic Scale')

Conclusion

The semilogx() function is a powerful tool for creating clear and readable plots of data that vary over a large range of values. It is a useful addition to the toolbox of any MATLAB programmer, and I hope this introduction has been helpful in demonstrating its capabilities.