How can I change the scaling of the y-axis on a semilogy plot?

Question

Nicholas Wong 2013-5-30

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Hello, I am having a problem with log plots and could use some kind assistance. Basically, I am plotting bit error rate (BER) curves for a telecommunications system. I have a vector for my y-axis (BER) values and a vector for the corresponding x-axis values. Using the semilogy command, I get my plot and it is fine. However, the y-axis tick marks (i.e. 10^-2, 10^-4, 10^-6, etc.) all have equal spacings between them. I am trying to find a way to scale the y-axis such that it is somewhat "to scale", that is, the spacing between 10^-6 and 10^-4 should be proportionately smaller than that between 10^-4 and 10^-2, and so on. I understand it is pointless for the spacings to be exactly proportional (lest the spacing between 10^-6 and 10^-4 would be 100 times smaller than that between 10^-4 and 10^-2!) but as long as it can be shown graphically that the spacings have been scaled, that will be good.

I would have like to attach some graphs as examples, but am unsure if Mathworks has this feature. Any help will be appreciated.

Kind regards,

Nicholas

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Answer 1

Azzi Abdelmalek 2013-5-30

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在 MATLAB Online 中打开

set(gca,'yscale','log')

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Nicholas Wong 2013-5-30

Thank you very much for the answer. It worked, though I had to manually convert my values into log scale and then use the plot command instead of semilogy. I did try it with a semilogy plot but there was no effect, probably because that is already in log-scale. Nevertheless, I got what I was after.

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Answer 2

Hadi Hajieghrary 2013-5-30

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Semilogx make the spacing between the ticks If you want the spacing be proportional you shouldn't then use the "semilog". As I understood you just want the ticks are placed on their real places, and just in logaritmic steps. Then do it in a simple plot command, and then go to the plot tool and place ticks wherever you want for the y-axis.