loglog
 logarithmic plot
In this example we are going to demonstrate how to use the 'loglog' function
included in Matlab to produce nonlinear
plots.
This term refers to the fact that the plot is
logarithmically scaled in both axes. There are other functions such as 'semilogx' and 'semilogy' which have
one axis in linear scale and the other axis in logarithmic scale.
1. Create a plot using a logarithmic scale for
both the xaxis and the yaxis (loglog):
clear;
clc; close all
%
Define your independent variable
t = 0 :
2*pi/360 : 2*pi;
%
Define values along your xaxis
x =
exp(t);
%
Define values along your yaxis
y = 50 +
exp(3*t);
%
Plot your function with a wider line and grid the figure
loglog(x,
y, 'LineWidth', 2)
grid
%
Use a title for the figure
title('Demonstration
of logarithmic plots')
%
Label your xaxis with a double line.
%
Note the special characters
xlabel([{'e^{t}'}; {'0
\leq t \leq 2\pi'}])
%
Label your yaxis
ylabel('50 +
e^{3t}')
The produced figure is:
2. Create a plot with a logarithmic scale for
the xaxis and a linear scale for the yaxis (semilogx):
% clear
memory data and command window
clear;
clc; close all
% define
your linear data
x = 0 :
1000;
% define
your logarithmic function
y =
log(x);
% plot
your log function on linear data
semilogx(x,
y)
% define
values of axes and grid
axis([1
1000 0 7])
grid
% add
relevant info
title('Example
of Semilogx')
xlabel('x')
ylabel('y
= log(x)')
The resulting figure is
3. Create a plot with a logarithmic scale for
the yaxis and a linear scale for the xaxis (semilogy):
clear;
clc; close all
% now
your data along the xaxis is linear
x = 0 :
0.5 : 10;
% your
function is now exponential
y =
exp(x);
% see
the plot
semilogy(x,
y)
plot
% add
info
title('Example
of Semilogy')
xlabel('x')
legend('y
= e^x')
The plot is
From
'loglog' to home
From
'loglog'
to '2D Plot Menu'
