How to work out the length of a line

I have a 'curved' line which is made up of 5 straight lines. How do I work out the total length of this line? Is this possible using a function in MATLAB.

[James Tursa]

How are these lines represented in MATLAB?

[J122]

I have the x and y coordinates of each point and when plotted the connections create straight lines, all at different angles.

Answer 1

[James Tursa]

%  x = your x coordinate vector
%  y = your y coordinate vector
%  d = diff([x(:) y(:)]);
  d = diff(your 3D point matrix); % EDIT
  total_length = sum(sqrt(sum(d.*d,2)));

[J122]

I have values [0 0 0; 1.5 1 0; 3 1.5 0; 5 1.5 0; 6.5 1 0; 8 0 0] which individually from one to another are straight lines but together is not a straight line , so i am wondering how to calculate the total length of a line connecting the points, from point 1 to point 6.

[Image Analyst]

What do the 6 rows and 3 columns represent? What is in columns? What is in rows? Which are x, and which are y and which are the points? Or is this (x,y,z) in 3-D, where rows are different 3-D points? You have to look at this from our point of view - we don't know what all those values in a 6 by 3 matrix are. How could we unless we guess or you tell us?

[J122]

sorry - each row is the 3d coordinates of a point on the plot i.e [x1 y1 z1; x2 y2 z2; x3 y3 z3...etc]. The full stops I have used in-between 2 numbers represent a decimal place e.g 1.5 and 6.5.

[J122]

As the z coordinate at each point is equal to 0 this can be treated as a 2d plot.

[James Tursa]

Answer edited to reflect your actual data storage.

[Simon Schulte]

What does this 'd.*d' do? I dont get the that point

[James Tursa]

d.*d does element-wise multiply ... i.e. it squares each value. Result is a matrix the same size as d. Could have gotten the same result with d.^2