how to set y-axis as log scale?

I am plotting x-y plot using plot function. I want to set only y-axis as log scale and x-axis as linear? How to do that? I used loglog function but it scales both axis but I want only Y.

Answer 1

[Walter Roberson]

The best way to create that type of axes is to use the semilogy function. Alternatively, you can set the ‘YScale’ property on the axes:

set(gca, 'YScale', 'log')

[Nick Durkee]

Note that this works for 3D plots as well. Not sure if there's an equivalence of semilogx for 3d.

[Walter Roberson]

set(gca, 'XScale', 'log')

[Mahender Aroori]

thank you

[M S Rashed]

Is there any way to convert from log-scale back to linera scale?

[Yang Yang]

set(gca, 'XScale', 'linear')

[In-chan Kim]

Is there a way to make set(gca, 'YScale', 'log') show negative values as well?

[Walter Roberson]

The log of negative real values is equal to the log of the positive value, plus (pi*1i) -- that is the result is complex. When you set YScale to log, then internally it would take the log of the negative values you have, and would found that the log is complex.

If, hypothetically, it were able to display with complex coordinates, where would you want the values displayed? For example do you want the complex portion of the coordinate to be treated as time, and the display should automatically cycle through a time period (perhaps every 2*pi seconds) with the negative values being displayed for one frame on each occasion that the complex value projected down to real?

If you want negative values to be displayed where the corresponding positive value would be displayed, then plot with abs(y) instead of y.

Remember, when you use log, there is an infinite distance in log scale between y = 1 and y = 0, since it has to pass through y = exp(-1), y = exp(-2), y = exp(-3), and so on, each of which needs to be allocated the same screen distance as between y = exp(0) and y = exp(1) . To get to negative y, you would have to go "further than infinity" down the bottom of the plot.

[Brad Norton]

what is gca?

[Walter Roberson]

https://www.mathworks.com/help/matlab/ref/gca.html

ax = gca returns the current axes or chart for the current figure, which is typically the last one created or clicked with the mouse.

Answer 2

[Elkin Javier Cepeda Ramirez]

thank you , you help me too much

Answer 3

[Hazem Mubarak]

Thanks ;)