Plot with two Y-axis and logarithmix scaling

Hi everybody

I am trying to construct a diagram with following code:

y1 = ....
y2 = ....
y3 = y2./y1
t = ...  

[ax, h1, h2] = plotyy(t,y1,y3,'loglog','plot');

set(h1,'LineWidth',2,'color',[1 0 0])
set(h2,'LineWidth',2,'color',[0 1 0])
set(ax(1),'FontWeight','Bold','LineWidth',1)
set(ax(2),'FontWeight','Bold','LineWidth',1)

set(get(AX(1),'Ylabel'),'String','TIME,h','FontSize',18,'fontweight','bold','fontname','times new roman')

set(get(AX(2),'Ylabel'),'String','0.2% CREEPSTRENGTH/RUPTURE STRESS,MPa','FontSize',18,'fontweight','bold','fontname','times new roman') 

axes(ax(2))
hold on
loglog(t,y2)

legend([y1 y2 y3],{'0.2% Creep strength','Rupture strength','L^{max}_r'},'Location','Southwest','fontname','times new roman','fontsize',20) 

xlim([10^3 10^4])

Explanation: I have the arrays y1,y2 which should be plotted on the left Y-axis, which has a logarithmic scale. y3 then should be plotted on the right Y-axis, which is non logarithmic. y1,y2,y3 all share the same X-axis t, which should also have a logarithmic scale.

I experience follwing issues:

• The scaling is somehow not correct
• I always have double sclaing for the X-axis
• I cant not set axis limiations
• I can not edit the colors of the Axis

I know this might be easy for some people, however I already have spent a lot of time on this and I can not get the correct solution

Thank you all!

Answer 1

[dpb]

y1,y2 should be plotted on the left Y-axis, which has a logarithmic scale. y3 then should be plotted on the right [linear] Y-axis... the ...X-axis t, ...should also have a logarithmic scale

Start with

hax= plotyy(t,[y1 y2],t,y3,'loglog','semilogx'); % save the two axes handles

and prettify from there...

doc plotyy % and friends for details on usage

BTW, the deal about two x-axes--yes, TMW leaves both x-axes visible and plotyy isn't smart enough internally to keep the two synchronized with each other so you have to modify both of them if modify one. Instead of dealing with that nuisance, I generally simply set the visible stuff non-so on the RH axis so while it's not consistent w/ the left it doesn't clutter up the rendition. You can do this by

set(hax(2),'xtick',[])   % clear tick value array for rh axes

which since there are then no tick values, causes h-graphics to not display any tick marks or tick labels for the second (right) x-axis. (I used to actually do this internally in my copy of plotyy() (not that I would recommend doing this by anybody else :) ) but now it's a p-file so can't do it except w/ a wrapper around plotyy).