Plotting powers of 10 on the colorbar

Hello,

Is there any way to have powers of 10 (like 1e5, 1e6, 1e7) to be plotted on the colorbar as tickmarks without resorting to using log10? I tried the following code.

col = colorbar('XTickLabel', {'10^{5}', '10^{6}', '10^{7}'}, 'XTick',1e10:1e11:1e12);
caxis([1e10 1e12])   

but that just gives me a colorbar with the xticks repeated as shown in colorbar.jpg (attached).

I also tried taking the log10 of these values as shown by the following code and got the desired output as shown in colorbar_log.jpg (attached):

col = colorbar('XTickLabel', {'10^{5}', '10^{6}', '10^{7}'}, 'XTick',log10(1e5):1:log10(1e7));
caxis([log10(1e5) log10(1e7)])   

I however was wondering whether the same output as in colorbar_log.jpg can be obtained without resorting to taking log10.

Thanks.

Answer 1

[Star Strider]

These are 'Ruler' properties, and they are not in the colorbar documentation. (I had to go searching for them, and then experiment.)

Try this —

[X,Y] = meshgrid(-1000:10:1000);
Z = exp(-(X.^2+Y.^2)/1E5)*1E6;

figure
surf(X,Y,Z, 'EdgeColor','none')
grid on
colormap(turbo)
hcb = colorbar;
% get(hcb);
hcb.Ruler.Exponent = 3;
hcb.Ruler.Scale = 'log';

See NumericRuler Properties for more details.

.

[Mathan]

Wow - thanks a bunch!

[Star Strider]

As always, my pleasure!

I also learned a bit more about MATLAB documentation in discovering that!

[Mathan]

Definitely - thank you again!

[Star Strider]

As always, my pleasure!

[Mathan]

Sorry but what does the 3 in hcb.Ruler.Exponent = 3 signify? I tried with different values other than 3 and am still receiving same outputs.

Thanks

[Star Strider]

As always, my pleasure!

That is the level of exponents displayed. It shows differently on linear scaling, however on the logarithmic scaling, it just has to be set to some value. See Exponent for more information on it.

[Mathan]

Definitely - thanks!

[Star Strider]

As always, my pleasure!

Answer 2

[Voss]

You can use naturlal log (log) or base-2 log (log2) (but I think log10 makes the most sense):

col = colorbar('XTickLabel', {'10^{5}', '10^{6}', '10^{7}'}, 'XTick',log(10.^(5:7))/log(10));
caxis([5 7])

figure();
col = colorbar('XTickLabel', {'10^{5}', '10^{6}', '10^{7}'}, 'XTick',log2(10.^(5:7))/log2(10));
caxis([5 7])

[Mathan]

Thank you - basically the same thing as log10 I guess.

[Voss]

Exactly. log10 with an extra log.