?
Solved

Can someone please see why I am getting this error?

Posted on 2009-03-30
3
Medium Priority
?
1,007 Views
Last Modified: 2016-02-10
I am new to Matlab and I am getting the following error;
Warning: Imaginary parts of complex X and/or Y arguments ignored
> In create_hyperbola at 13
Warning: Imaginary parts of complex X and/or Y arguments ignored
> In create_hyperbola at 15

what does this mean and why is this?

thanks in advance
% Program to plot the hyperbola
% y^2/a^2 - x^2/b^2 = 1
% The hyperbolae are open up/down, so that x is the independent variable
% for plotting. (Using the form x^2/a^2 - y^2/b^2 = 1 requires that y be
% the independent variable, which is awkward programming-wise.)
clear % all variables
figure(1), hold off % start a new figure
set(gca,'FontSize',14) % adjust fontsize
xmax = 30; ymax = 20;
x = linspace(-xmax,xmax,1001); % array of x values for plot (why 1001?)
a = 5; b = 3;
y=sqrt(((-x.^2)./(b^2)+1).*a^2); % corresponding y values
plot(x,y)
hold on % add to current plot
xlabel('x')
ylabel('y')
title(['Hyperbola $y^2/a^2 - x^2/b^2 = 1$; $a$ = ', num2str(a), ...
', $b$ = ', num2str(b),'; (WR 1/21/08)'],'Interpreter','latex')
% Add axes
plot([0 0],[-ymax ymax],'k') % y axis (black line - k)
plot([-xmax xmax],[0 0],'k') % x axis

Open in new window

0
Comment
Question by:jtiernan2008
  • 2
3 Comments
 
LVL 15

Expert Comment

by:yuk99
ID: 24021978
This is because when you calculating y (line 12) you getting square root mostly from negative numbers. So your y is vector of complex numbers. You get this because when you do -x.^2, it gets square first, than adds minus.
Do (-x).^2.
0
 
LVL 15

Accepted Solution

by:
yuk99 earned 2000 total points
ID: 24022077
Actually you will get different result. You probably just need what you get, but worry about the warning? Just ignore it, or you can get real part from complex y with real(y).

So in your code line 13 use:
plot(x,real(y))
0
 
LVL 1

Author Closing Comment

by:jtiernan2008
ID: 31564470
thanks a million
0

Featured Post

[Webinar] Database Backup and Recovery

Does your company store data on premises, off site, in the cloud, or a combination of these? If you answered “yes”, you need a data backup recovery plan that fits each and every platform. Watch now as as Percona teaches us how to build agile data backup recovery plan.

Question has a verified solution.

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

Whether you’re a college noob or a soon-to-be pro, these tips are sure to help you in your journey to becoming a programming ninja and stand out from the crowd.
Article by: evilrix
Looking for a way to avoid searching through large data sets for data that doesn't exist? A Bloom Filter might be what you need. This data structure is a probabilistic filter that allows you to avoid unnecessary searches when you know the data defin…
This tutorial explains how to use the VisualVM tool for the Java platform application. This video goes into detail on the Threads, Sampler, and Profiler tabs.
The viewer will learn how to pass data into a function in C++. This is one step further in using functions. Instead of only printing text onto the console, the function will be able to perform calculations with argumentents given by the user.
Suggested Courses

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

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

Join & Ask a Question