I have plotted to vectors against each other, and they are already logarithmic and everything is fine with that. But now that I have my plot i want the grid to be logarithmic. I write "grid on" in my code, and I think there should be a way to do this in the plot, but I can't remember how. How do I make the grid logarithmic?
If you use loglog, semilogx or semilogy instead of plot, the grid will automatically be on a log scale for the corresponding axes when using grid on.
If you have already plotted the axes, you can execute the following on the command line:
set(gca,'yscale','log') %# to set the y-axis to logarithmic
set(gca,'xscale','log') %# to set the x-axis to logarithmic
Have a look at axes properties to find out what else you can modify.
Related
Is it possible to make a plot in matlab that does not actually take the logs of the values? I'm plotting wide ranges of values and when I try to make a log plot of them, those below 1 become negative. I would just like it to plot the values on a log scale without taking their logs.
Alternatively, set(gca,'XScale','log') if you have your plot already.
Yes, it is possible. Use the loglog command.
The example from the Mathworks website:
x = logspace(-1,2); % generate a sequence of points equally spaced logarithmically
loglog(x,exp(x),'-s')
grid on
If you do not want both axes to be log scale, use semilogx or semilogy.
So, you want to plot liner data on logarithmic axes? You can exponentiate you values before using the log plot. This way the point p=(10,3) will plot at the x=10 position.
I'm the MatLab newbie and I need some help to create a linear and non-linear axis in one chart.
I need to make chart with 2 different X-axes. One X-axis displays 1000/T at the bottom and the second X-axis displays a T at the top of the chart.
Example figure:
Do you have any idea how to solve this problem in MatLab?
Thanks.
This can be done by simply creating a second axes object at the same place as the first. Let's first create some data:
x1 = 1:0.1:3.5;
x2 = 1./x1;
y = (0.5*(x1-2)).^3;
Now we can create a normal plot with the first axes, and get the axes handle:
plot(x1,y,'-r');
ax(1) = gca;
Then we create the second axes object, at the same position as the first, and make the color none so it is transparent and the plot from below is still visible. As this adds a second Y axis too, we simply remove the Y ticks of the second axis.
ax(2) = axes('Position',ax(1).Position,'XAxisLocation','top','Color','none');
set(ax(2),'YTick',[]);
Now lets just format the second X axis as we like. Let's set the limits to the minimum and maximum of the x2 vector, and make it logarithmic:
set(ax(2),'XLim',[min(x2),max(x2)]);
set(ax(2),'XScale','log');
Now we still have the problem that the XTicks of ax(1) are also displayed at the top, and the XTicks of ax(2) are displayed at the bottom. This can be fixed by removing the box around the existing axes and creating a third axis without any ticks but with a box.
box(ax(1),'off');
box(ax(2),'off');
ax(3) = axes('Position',ax(1).Position,'XTick',[],'YTick',[],'Box','on','Color','none');
Now finally we can link the axes to be able to zoom correctly
linkaxes(ax);
And that should be it...
There is documentation for having a graph with two y-axes on the Mathworks website . .
http://de.mathworks.com/help/matlab/creating_plots/plotting-with-two-y-axes.html
It should be trivial to covert the concepts to the x-axis.
I have two plots. The x-axis for both is same, however the y-axis is different. I would like to plot both plots in one plot in a way that they share the same x-axis. x-axis represents time for both graphs. Any suggestions how to do that instead of plotting each one alone. The following picture shows what I'm looking for.
you can use subplot and delete the x-axis tick labels of the top one, for example:
x=rand(1,100);
subplot(2,1,1);
plot(1./x);
ylabel('Label 1')
set(gca,'XTickLabel',[])
subplot(2,1,2);
plot(x)
ylabel('Label 2')
xlabel('x Label')
If you want the plots to be closer to one another you can use one of the FEX files such as subplot_tight etc (for example this one , or this one)
Or you can just use axes...
I have plotted to vectors against each other, and they are already logarithmic and everything is fine with that. But now that I have my plot i want the grid to be logarithmic. I write "grid on" in my code, and I think there should be a way to do this in the plot, but I can't remember how. How do I make the grid logarithmic?
If you use loglog, semilogx or semilogy instead of plot, the grid will automatically be on a log scale for the corresponding axes when using grid on.
If you have already plotted the axes, you can execute the following on the command line:
set(gca,'yscale','log') %# to set the y-axis to logarithmic
set(gca,'xscale','log') %# to set the x-axis to logarithmic
Have a look at axes properties to find out what else you can modify.
Is it possible to make a plot in matlab that does not actually take the logs of the values? I'm plotting wide ranges of values and when I try to make a log plot of them, those below 1 become negative. I would just like it to plot the values on a log scale without taking their logs.
Alternatively, set(gca,'XScale','log') if you have your plot already.
Yes, it is possible. Use the loglog command.
The example from the Mathworks website:
x = logspace(-1,2); % generate a sequence of points equally spaced logarithmically
loglog(x,exp(x),'-s')
grid on
If you do not want both axes to be log scale, use semilogx or semilogy.
So, you want to plot liner data on logarithmic axes? You can exponentiate you values before using the log plot. This way the point p=(10,3) will plot at the x=10 position.