# Get x axis value at point matlab

Hello all,
I am trying to plot a circle at the min point of a plot. I am able to find the Y min value, however, I am trying to find the value of the X-axis at this point.

Thank you
``````clear all;
R=1600;
L=120e-6;
C=100e-9;

num = [R*L*C 0 R];
den = [R*L*C L R];

subplot(2,1,1)

system=tf(num,den);
[mag,phase]=bode(system,{2.8e5,3e5});

mag=db(mag);
[minvalue,minIndex]=min(mag);

hold on;
bodemag(system,{2.8e5,3e5});
title('Bode plot for question 1');
plot(??,minvalue,'mo');

subplot(2,1,2);
h=bodeplot(system,{2.8e5,3e5});
setoptions(h,'MagVisible','off');
title('');
hold off;
``````
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Commented:
Use second output argument of MIN function to get index of the point at minimum:

[ymin, idx] = min(y);
xmin = x(idx);
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Author Commented:
Hello yuk99,
Thanks for the reply. I tried that and keep getting error message:

??? Undefined function or method 'x' for input arguments of type 'double'.
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Commented:
How do you create the plot? What is x and y variables. In my example I used variable x as x coordinates and y as y coordinates. If you use different variables, use yours instead. Show your code to draw plot if you still have problems.
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Commented:
Sorry, I read the question on my smartphone and didn't see the code. So my accepted answer doesn't actually answer the question.

Here is another answer that should work in case you don't know x and y of your plot, but want to show minimum point on the plot::

``````hold on
bodemag(system,{2.8e5,3e5});
h = findobj(gca,'type','line');
for ii=1:numel(h);
x = get(h(ii),'XData');
if numel(x)==0 || any(isnan(x))
continue
end
y = get(h(ii),'YData');
break
end
[minValue,minIndex]=min(y);

plot(x(minIndex),minValue,'mo');
hold off
``````
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