Solved

# Get x axis value at point matlab

Posted on 2010-11-17
Medium Priority
999 Views
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;
``````
0
Question by:dwb178
[X]
###### Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

• Help others & share knowledge
• Earn cash & points
• Learn & ask questions
• 3

LVL 15

Accepted Solution

yuk99 earned 2000 total points
ID: 34161314
Use second output argument of MIN function to get index of the point at minimum:

[ymin, idx] = min(y);
xmin = x(idx);
0

LVL 1

Author Comment

ID: 34161458
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'.
0

LVL 15

Expert Comment

ID: 34161544
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.
0

LVL 15

Expert Comment

ID: 34327984
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
``````
0

## Featured Post

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When we want to run, execute or repeat a statement multiple times, a loop is necessary. This article covers the two types of loops in Python: the while loop and the for loop.
Q&A with Course Creator, Mark Lassoff, on the importance of HTML5 in the career of a modern-day developer.
The goal of the video will be to teach the user the difference and consequence of passing data by value vs passing data by reference in C++. An example of passing data by value as well as an example of passing data by reference will be be given. Bot…
Viewers will learn how to properly install Eclipse with the necessary JDK, and will take a look at an introductory Java program. Download Eclipse installation zip file: Extract files from zip file: Download and install JDK 8: Open Eclipse and …
###### Suggested Courses
Course of the Month15 days, 4 hours left to enroll

#### 649 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.