Mesh Plot

I am attempting to plot the equation X^2 + 4*Y^2 < 1, using the mesh function. I currently have the code

[X,Y] = meshgrid(-1:.25:1);
Z = ((X.^2 + 4 * Y.^2) );
mesh(X,Y,Z)

However, this does not follow the requirement of Z < 1. How would I accomplish this?

Answer 1

[the cyclist]

I don't understand why you expect Z to be less than 1, since your definition of Z clearly has a maximum of 5.

However if you only want to plot values of Z that are less than 1, then you could substitute "NaN" where Z>=1, like this:

Z(Z>1) = NaN

and then do your mesh plot.

[Sean de Wolski]

z(z>=1)=nan

[Tyler]

Thank you both for you quick reply.

However, trying your suggestion, I do not receive the graph I am anticipating. Adding the Z(Z>1) = NaN (or Z(Z>1) = NaN) seems to cut off the plot at a size smaller than wanted. I am assuming to see a bowl-shaped plot, but with this added code it looks more like a banana.

[Sean de Wolski]

Perhaps you wanted

Z(Z>1) = 1;

so that it shows as one instead of blank?

[the cyclist]

Well, the equation is what it is. Maybe if you plotted a finer mesh it would be better. Also, consider using the view() command to change the perspective.

[Tyler]

I am unfamiliar with the finger mesh, how would that help me? I understand that my original graph was correctly plotting the equation I have given it, but my desired equation of X^2 + 4*Y^2 < 1 does not appear to be a valid equation.

[the cyclist]

Also, the "4" in your equation is definitely going to mean that the shape is not very symmetrical between X and Y. Is that 4 really supposed to be there?

[the cyclist]

Sorry! I made a typo of "finger mesh" instead of "finer mesh". I corrected it.

[Sean de Wolski]

http://www.mathworks.com/matlabcentral/fileexchange/16728-fingerprint-application

finger meshing!