14.4: Log plots

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Page ID: 110906

Carey Smith
Oxnard College

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When plot values cover more than 1 order of magnitude, it can be more useful to create a logarithm plot rather than a standard lineat plot.

The MATLAB and Octave functions for logarithm plots are semilogx(), semilogy(), and loglog(). The following examples illustrate the use of these functions.

Example \(\PageIndex{1}\) semilogy(), log(), semilogx()

% Log plot examples

% Create data
x = 0:5
y = 2*3.^x

%% Standard linear plot
figure;
plot(x,y,'-s')
title('Standard linear plot of y = 2*3.^x')
grid on

%% semilogy plot
figure;
semilogy(x,y,'-s')
title('semilogy plot of y = 2*3.^x')
grid on

%% semilogx plot
figure;
semilogx(x,y,'-s')
title('semilogx plot of y = 2*3.^x')
grid on
%% loglog plot
figure;
loglog(x,y,'-s')
title('semilogy plot of y = 2*3.^x')
grid on

Solution

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