Determine the maximum with indexax function (plotyy)

Hello,

I have following Problem:

First at all in my workspace I have 3 times 5696x1 double values. These datas are: time, power and distance. I plot these 3 datas with the plotyy function.

[ax,p1,p2] = plotyy (time,power,time,distance);

Now I want to determine the (y)maximum of the distance and add a text. Therefore I want to use the indexmax function but it does not describe the problem for 2 y axes.

indexmax = find(max(Y2) == Y2);
xmax=x(indexmax);
ymax=y(indexmax;

• "Error in graph (line 8) xmax=x(indexmax);"

Thanks

Answer 1

[Kevin]

Thanks for your help,

Y2 ->

plotyy(X1,Y1,X2,Y2)

indexmax = find(max(Y2) == Y2);

should be:

indexmax = find(max(distance) == distance);

Nevertheless your code

[dmx,idx]=max(distance);  % the distance max, location

works.

[dmx,idx]=max(Weg_mu_meter) % max. Abstand, Matrixzeile
tmx=Zeit(idx)           % Zeit des maximalen Abstands
text(tmx,dmx,num2str([dmx tmx],'Max D=%.1f at %.1fsec'))

Result:

dmx =

   23.5753

idx =

        5130

tmx =

   75.0820

I uploaded an image of the plot. The text is on the bottom right of the image. How can I put in next to the maximum?

Is it possible that dmx idx and tmx can give me out the numbers with the unit. Like s for second...

[dpb]

Yes, because you didn't use the handle of the RH axes so the y value is plotted at 23.6 on the LH axes which you note is about the right vertical position on that axis. As I showed, use the handles...

hAx=plotyy(Zeit,????,Zeit,Weg_mu_meter);  % don't know other variable
[dmx,idx]=max(Weg_mu_meter) % max. Abstand, Matrixzeile
tmx=Zeit(idx)           % Zeit des maximalen Abstands
text(hAx(2), tmx,dmx, ...
     num2str([dmx tmx],'Max D=%.1f at %.1fsec'), ...
     'horizontalalignment','right', ...
     'verticalalignment','bottom')

There are no inherent units associated with arrays/matrices in Matlab; you have to know what those units are and code them as shown. You can use TeX/LaTeX interpreter in text for greek for the distance as you did in the ylabel text.

Recent releases include the timeseries object/class http://www.mathworks.com/help/matlab/ref/timeseries-class.html which does have a time basis property associated with it that can be set/retrieved. Not sure precisely when introduced--I'm at R2012b which does include it (or at least an early release; I've never tried it).

Answer 2

[dpb]

What's Y2???

[dmx,idx]=max(distance);  % the distance max, location
tmx=time(idx);            % time of max distance
text(ax(2),tmx,dmx,num2str([dmx tmx],'Max D=%.1f at %.1fsec')

Fixup format string to suit, obviously, plus may want/need to adjust location/offset to avoid clutter. See

doc text

for details.