How to get final value from iteration rather than block of numbers

Question

Holly Martin 2019-11-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/492737-how-to-get-final-value-from-iteration-rather-than-block-of-numbers

评论： Holly Martin 2019-11-23

Hi, Ive written code for Eulers method for an equation of motion for an academic assignment, and I need to return values for z (position) , v (derivative of z) and my student number, using a function with the inputs shown below.

this is the code i have so far:

function [z,v,studentid] = particle(m,g,k,p,V,h,N)
%Numerical Solution
%This function will integrate the equation of motion using the
%forward Euler time stepping method.
% Input params needed from task 1
for studentid=690022044;
g=9.4000;
k=0.1000;
p=1.2000;
m=5;
% Initial conditions and setup
h = 0.1;  % step size
t = 0:h:10;  % the range of t
z = zeros(size(t));  % allocate the result z
z(1) = 1;  % the initial z value
N = numel(z);  % the number of z values
% The loop
for i=1:N-1
    v=diff(z);
    v(i+1) = v(i) + h*(((-g-k*(abs(v(i)).^p)*v(i)/m)));
    z(i+1) = z(i)+h*v(i+1);
end
end
%testing
plot(t,v)
xlim([0 9.8])
end

I run it and it works, but it gives me the columns of values as it iterates and doesnt give me z, v and my student number.

Any help would be really appreciated, thanks :)

Holly

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Answer 1

David Hill 2019-11-23

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/492737-how-to-get-final-value-from-iteration-rather-than-block-of-numbers#answer_402936

在 MATLAB Online 中打开

function [z,v,studentid] = particle(m,g,k,p,h)%V and N were not needed as inputs to your function
studentid='690022044';
t = 0:h:10;  
z = zeros(size(t));  
z(1) = 1;  
N = numel(z);  
for i=1:N-1
    v=diff(z);
    v(i+1) = v(i) + h*(((-g-k*(abs(v(i)).^p)*v(i)/m)));
    z(i+1) = z(i)+h*v(i+1);
end
end

Once your run your function,

[z,v,studentid]=particle(5,9.4,.1,1.2,.1);

You can display the final values of z, v, and studentid by typing:

disp(z(end));
disp(v(end));
disp(studentid);

Or if all you want is the final values, then:

function [z,v,studentid] = particle(m,g,k,p,h)%V and N were not needed as inputs to your function
studentid='690022044';
t = 0:h:10;  
z = zeros(size(t));  
z(1) = 1;  
N = numel(z);  
for i=1:N-1
    v=diff(z);
    v(i+1) = v(i) + h*(((-g-k*(abs(v(i)).^p)*v(i)/m)));
    z(i+1) = z(i)+h*v(i+1);
end
z=z(end);%add these
v=v(end);
end