How to make equation work for each frame of data?

Hey guys! I have walking data that I am trying to calculate joint angles for. The data I have has two colums of 134 rows that I need the equations to calculate for each frame of data. I do not know how to do this. I assume I'll need some for of a loop to do so.

[Jan]

Answered here: https://www.mathworks.com/matlabcentral/answers/1919840-how-to-create-a-vector-for-multiple-frames-of-data-in-rows-and-columns

[David Hill]

What is the equation?

Answer 1

[William Rose]

@Amanda,

[edit: correct error in my code]

This looks like something I would have assigned when I taught biomechanics or when I taught a graduate course in advanced biomechanics.

You have sagital plane data for right hip, knee, ankle, foot. You do not need a for loop. Matlab is good at avoiding the need for for loops.

What happens when you run your code? Do you get an error? What is it?

You did not supply the csv file. You only supplied the PDF, which is not useful.

It looks like you are not using the necessary syntax for indexing the matrices. Let's assume the following code works (which I cannot verify, since I don't have the CSV file):

data = readmatrix('2D_kinematics_2022.csv');  %read data from file
RGRT = data(:,1:2);  %x,y for R greater trochanter
RLCO = data(:,3:4);  %x,y for R knee lateral epicondyle

Compute the angle of the thigh vector relative to horizontal:

thighAngle=atan2(RLCO(:,2)-RGRT(:,2),RLCO(:,1)-RGRT(:,1));

Try it and apply that idea to the other angles, including joint angles.

[Jan]

@Amanda: You find the same solution in your other thread: https://www.mathworks.com/matlabcentral/answers/1919840-how-to-create-a-vector-for-multiple-frames-of-data-in-rows-and-columns#comment_2638220 . This is the drawback of duplicate questions: The answering persons waste time for posting solutions repeatedly. Please avoid this in the future.

[William Rose]

@Jan, thank you.