finding magnitude of a vector

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Ashlianne Sharma 2020-11-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/639990-finding-magnitude-of-a-vector

评论： Ashlianne Sharma 2020-11-8

Hi all, I am trying to make a function and the first step within my function is to find the magnitude of a vector that I have named on another script. How do I do this? I willo put my code below to explain more.

FROM FUNCTION PAGE

function[a, e, nu, i, O, m] = hw_COE_sharmaAshlianne(R, V)
 
% Inputs 
% R = Radius vector     [km]
% V = Velocity vector   [km/s] 
% 
% Outputs 
% a = semi major axis           [km]
% e = eccentricity              [no units]
% nu = true anomoly             [degrees]
% i = inclination               [degrees]
% O = right ascention of the ascending node(RAAN)  [degrees]
% w = argument of perigee       [degrees]
 
% Known values
m = 398600;          % [km^3/s^2]
 
% Step one find the magnitude of the radius and velocity vectors
r = norm(R);
v = norm(V);

FROM SCRIPT

% Create a structure for our function to find COE parameters
Rvector = [15370 1400 21950];   % [km]
Vvector = [-0.1 3.84 -0.2];     % [km/s]
 
% Call function with the structured variables we created above
[a, e, nu, i, O, m] = hw_COE_sharmaAshlianne(Rvector, Vvector);

so to reiterate my question, how do I find the magnitude of Rvector that is defined in my script on my function page (STEP ONE IN FUNCTION)

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Ashlianne Sharma 2020-11-8

Okay, so you had an amzing explaination for the norm aspect, thank you so much.

This question seems simple, But I struggle with this since the start of the class.

Script %note I changed Rvector to R for simplicity

% Define given vectors as variables

R = [15370 100 21950]; % [km]

V = [-0.1 3.84 -0.2]; % [km/s]

% Call function with the structured variables we created above

[a, e, nu, i, RAAN, w] = hw_COE_sharmaAshlianne(R, V);

Function: line one, after this line, I finished the rest of my code.

function[a, e, nu, i, RAAN, w] = hw_COE_sharmaAshlianne(R, V)

Question:

When I was getting your help, I just defined my vectors inside my function. Like you say above, you dont need to do this. I took out my defined vectors from my function and I now get an error message saying I do not have enough input arguments. I don't know how to pass the variables through. Like I know the variables have to be the same on the script and function page, But that isnt working for me. Any explaination on passing variables through the function would be great help... The matlab version online hasnt been too much of help. Thank you Vasishta!

VBBV 2020-11-8

编辑：VBBV 2020-11-8

在 MATLAB Online 中打开

https://in.mathworks.com/help/matlab/ref/function.html

Check the syntax of function declaration. You require space between the word function and output variable vector

%if true
  % code
%end
function [a,e,nu,i,O,m]=
w_COE_sharmaAshlianne(Rvector,Vvector)
...
r = norm(Rvector);
v = norm(Vvector)
...
end % close function file with end statement

Ashlianne Sharma 2020-11-8

Okay, Thank you so much for your help!! i will definitely look more to the page you sent me, I think that may be very useful. Again, Thank you so much for taking So SO much time out to help me. I am just a struggling college student haha but yes, I really appreciate your time and help Vasishta!

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