How to get the ticks for each value of the logarithmic scale?

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Hi,
I'm learning to read logarithmic graphs and haven't found anywhere what the ticks between 10^0 and 10^1 for instance are (they are not 10^.1, 10^.2, etc because the gap becomes smaller, and not larger...) and how to plot them in Matlab. Any help appreciated.

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Star Strider
Star Strider 2018-2-26
The ticks between 10^0 (or 1) and 10^1 (or 10) are the integers between 1 and 10. They are scaled logarithmically, so the apparent distance between them appears to decrease.
This example code:
x = linspace(0.1, 1.0, 10);
y = x;
figure(1)
semilogx(x, y)
ax = gca;
ax.XMinorTick = 'on';
ax.XAxis.TickValues = x;
ax.XAxis.Exponent = 1;
xlabel('Logarithmic X-Axis')
ylabel('Linear Y-Axis')
title('Illustrating Logarithmic Scaling')
produces this plot:
  4 个评论
Tahariet Sharon
Tahariet Sharon 2018-2-26
Thanks. I still don't understand why there is a bigger gap from 10Hz to 20 Hz than from 70Hz to 80Hz.
Star Strider
Star Strider 2018-2-26
My pleasure.
The decreasing gaps are due to plotting logarithmic values on a linear scale (which is what the semilog axis does).
Consider:
Xtix = log10(10:10:100)
DiffXTix = diff([0 Xtix])
Xtix = 1.0000 1.3010 1.4771 1.6021 1.6990 1.7782 1.8451 1.9031 1.9542 2.0000
DiffXTix = 1.0000 0.3010 0.1761 0.1249 0.0969 0.0792 0.0669 0.0580 0.0512 0.0458
You can see that the differences between the logarithm values decrease as the values themselves increase. That is the nature of logarithms, and what the plot illustrates.

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