How to display arc length of the line created on a line plot based on the input data

Hi,

I am currently plotting a series of x and y co-ordinates using the plot(x,y) function in MATLAB which outputs a graph that looks something like this:

How do I go about displaying the arc length of the line created at points along the line assuming my first x and y data point is 0% and my last data point is 100%?

[Adam Danz]

The goal isn't quite clear. Is "arc length" some segment of the semi-circular area or are you asking for the entire length of the black line?

[jessupj]

i think you want something along the lines of the cumulative sum of the pythagorean distances between successive points on the curve, normalized by the final term.

Answer 1

[Voss]

% some x and y:
x = [10:-1:2 2:10];
y = [5+sqrt(x(1:end/2)) 5-sqrt(x(end/2+1:end))];
plot(x,y,'-o');
set(gca(),'XLim',[0 12]);

% calculate "normalized arc length":
dx = diff(x);
dy = diff(y);
ds = sqrt(dx.^2+dy.^2);
s = cumsum([0 ds]);
s = s/s(end);

% put a text at each x,y with value of s:
v_a = {'top','bottom'};
nx = numel(x);
for i = 1:nx
    text(x(i),y(i),sprintf('%d%%',round(100*s(i))),'VerticalAlignment',v_a{1+(i>nx/2)});
end