Logarithmic scale with a different base

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Ido Gross
Ido Gross on 13 Aug 2020
Answered: Joshua Carmichael on 13 Aug 2021
Hi,
I am trying to plot a function using logaritmic scale on the x axis, with base 2.
my code is:
N = 1:10000;
M = 61;
L = N-M+1;
ova_complex = ((N.*(log2(N)+1))./(N-M+1));
figure
stem(log2(N),ova_complex)
xlim([6 14])
the graph im getting is good, but i want to show only the integer values on the x axis(i.e. 6,7,8,9)
is there a way to do that?
thanks

Answers (4)

Star Strider
Star Strider on 13 Aug 2020
Try this:
N = 1:10000;
M = 61;
L = N-M+1;
ova_complex = ((N.*(log2(N)+1))./(N-M+1));
figure
stem(log2(N),ova_complex)
xlim([6 14])
xt = get(gca, 'XTick'); % ADD THIS LINE
xtl = fix(min(xt)):fix(max(xt)); % ADD THIS LINE
set(gca, 'XTick',xtl) % ADD THIS LINE
That should produce integer ticks and integer tick labels.
.

hosein Javan
hosein Javan on 13 Aug 2020
add the following after plot
ax = gca; % current axe
ax.XTick = 6:14;

Walter Roberson
Walter Roberson on 13 Aug 2020
log2(x) = log(x) *log(2)
log(2) is a uniform scaling and since plots are scaled to fit available space, becomes irrelevant.
So you get the same shape if you use semilogx. And you can lie with the labels if you want. However if you are using datatips you need your approach (unless you program them to lie)
You can use xticks() to choose integer tick locations.

Joshua Carmichael
Joshua Carmichael on 13 Aug 2021
For a natural log base, try:
logspace(0, log10(exp(1)),100)
To generate a spaced set of 100 samples that start at one and terminate at e^(1).

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