Need Help to find the error

Hello, I need from an array consisting of 10,000 items and are the coordinates (X and Y) of the ellipse to determine the minimum and maximum distance between two points. The problem is that the origin of 10000 should have 9999 range, the mine, the program calculates only 9998. you can verify using the command size(dist).

 clear all
clc
A=[2/3 -2/3; 2/3 7/3];
 [eigenvektor, eigenvalue]=eig(A);
 n = 10000;
 theta = linspace(0,2*pi,n);
 r = 1;
 x =r.*cos(theta);
 y =r.*sin(theta);
 plot(x,y,'.')
 v = [x;y];
 w=A*v;
xcoor=w(1,:);
ycoor=w(2,:);
i=0;
while i<n
i=i+1;
dxx2=xcoor(n-i:length(xcoor)-i);
dxx1=xcoor(n-(i+1):length(xcoor)-(i+1));
dyy2=xcoor(n-i:length(ycoor)-i);
dyy1=xcoor(n-(i+1):length(ycoor)-(i+1));
dist(i)=sqrt( (dxx2-dxx1)^2 +    (dyy2-dyy1)^2);
end

[Azzi Abdelmalek]

which distance do you want, maybe there is a better way to do it

[Alex]

distance between two points of the ellipse. The circumference of an ellipse has 10 000 points. maxdistance=max(dist) maxdistance =0.0008378

mindistance=min(dist) mindistance = 6.581D-08 The formula for the distance set me right. The problem is that in its cycle, I do not get to a end of the array.

Answer 1

[Azzi Abdelmalek]

r = 1;
x =r.*cos(theta);
y =r.*sin(theta);
plot(x,y,'.')
v = [x;y];
w=A*v;
xcoor=w(1,:);
ycoor=w(2,:);
figure,plot(xcoor,ycoor)
dist=sqrt(xcoor.^2+ycoor.^2)*2
min(dist)
max(dist)

If the origin of your ellipse is not (0,0) we can make translation

Also you don't need 10000 points, 5000 points are enough

dist=sqrt(xcoor(1:5000).^2+ycoor(1:5000).^2)

[Alex]

Not sure that is correct ... As I understand it from the task to determine the distance between two adjacent points in the plane of the ellipse, rather than minimum and maximum distance between any two points in the plane of the ellipse. "The set of vectors w contains vectors with maximal and minimal length (Euclidean norm). Compute these two values" or am I wrong again?

[Azzi Abdelmalek]

do you want the distance between two consecutive points?

then look at Star's answer

[Alex]

thank you very much:)

Answer 2

[Star Strider]

Instead of your while loop, I suggest:

dxx = diff(xcoor);
dyy = diff(ycoor);
dist = hypot( dxx, dyy);

Does this do what you want?