How do I store the x's, the v's and the F's from this for loop into an array??? pls and ty

x=0; %position of the leaf in meters

v=.5;  %the velocity of the leaf in meters/seconds

m=0.3; %mass of the leaf in kilograms

t=(0:0.05:3);

h=0.05;

int=0;                      %the intial time for graphing

%for

for I=(1:60)                %Number of instances which is 0 to 3 seconds of steps of .05

   %Plot
   subplot(1,3,1)
   plot(int,x,'.r')            %Graph of position over time
   hold on
   subplot(1,3,2)
   plot(int,v,'.r')
   hold on

    %Equations
    F=0.2*(sin(x))*((x^2)+x); %Force equation
    a=F/m;                    %acceleration equation

    x=x+h*v;%New Position
    v=v+h*a; %New Velocity

   subplot(1,3,3)
   plot(int,F,'.r')
   hold on

   int=int+0.05;
end

Answer 1

[Julia]

Hi,

I just modified your code so that you can store the values for x, v and F.

x=zeros(1,61);
v=zeros(1,61);
F=zeros(1,60);
x(1)=0; %position of the leaf in meters

v(1)=.5; %the velocity of the leaf in meters/seconds

m=0.3; %mass of the leaf in kilograms

t=(0:0.05:3);

h=0.05;

int=0; %the intial time for graphing

%for

for I=(1:60) %Number of instances which is 0 to 3 seconds of steps of .05

     %Plot
     subplot(1,3,1)
     plot(int,x(I),'.r')            %Graph of position over time
     hold on
     subplot(1,3,2)
     plot(int,v(I),'.r')
     hold on

      %Equations
      F(I)=0.2*(sin(x(I)))*((x(I)^2)+x(I)); %Force equation
      a=F(I)/m;                    %acceleration equation

      x(I+1)=x(I)+h*v(I);%New Position
      v(I+1)=v(I)+h*a; %New Velocity

     subplot(1,3,3)
     plot(int,F(I),'.r')
     hold on

     int=int+0.05;

end

[Stephen]

+1 for a very nice example of array preallocation.

[Andrew Holland]

Ok now if I wanted to plot the now allocated arrays (X,V,F) with points connected in a line, how would I do so?

Since X,V,F aren't arrays that can be plotted in a line or am I not in full understanding of the arrays created?

[Andrew Holland]

This is what I currently have

%Problem4

%Clear Everything

clear,clc,clf

x=zeros(1,61);

v=zeros(1,61);

F=zeros(1,61);

x(1)=0; %position of the leaf in meters

v(1)=.5; %the velocity of the leaf in meters/seconds

m=0.3; %mass of the leaf in kilograms

t=(0:0.05:3);

h=0.05;

int=0; %the intial time for graphing

%for

for I=(1:60) %Number of instances which is 0 to 3 seconds of steps of .05

     %Plot
     subplot(1,3,1)
     plot(int,x(I),'.r')            %Graph of position over time
     hold on
     subplot(1,3,2)
     plot(int,v(I),'.r')
     hold on

     %Equations
      F(I)=0.2*(sin(x(I)))*((x(I)^2)+x(I)); %Force equation
      a=F(I)/m;                    %acceleration equation
      x(I+1)=x(I)+h*v(I);%New Position
      v(I+1)=v(I)+h*a; %New Velocity

     subplot(1,3,3)
     plot(int,F(I),'.r')
     hold on
     int=int+0.0525;                % to make the x axis look nice

end

%Print

    fprintf('The location of the particle after 3 seconds is %0.4f\n',x(end))

    %Labels

    subplot(1,3,1)

    title ('Position vs Time')

    xlabel ('Time (s)')

    ylabel ('Position (m)')

    subplot(1,3,2)

    title ('Velocity vs Time')

    xlabel ('Time (s)')

    ylabel ('Velocity (m/s)')

    subplot(1,3,3)

    title ('Force vs Time')

    xlabel ('Time (s)')

    ylabel ('Force (N)')

[Julia]

Hi,

use an array for int and plot your graphs outside of the loop - for a line graph don't put a '.' in front of the r:

   subplot(1,3,1)
   plot(int,x,'r')            %Graph of position over time

   subplot(1,3,2)
   plot(int,v,'r')

   subplot(1,3,3)
   plot(int,F,'r')