Plot a line between two points with given angle which points its direction.

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Arsal15 2015-12-21

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评论： Star Strider 2016-1-24

I need your guidance that how I can compute angle between two points and draw a direction vector to get the direction of these two colored lines(Pink,Blue) at each instant of time.

Secondly is it possible that I can extract the speed as I am given (x,Y) position and time (as can be seen from the figure which is plotted on X,Y plane in a given time)?

Thanks in advance for your kind reply.

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Answer 1

Star Strider 2015-12-21

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quiver

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Star Strider 2016-1-21

在 MATLAB Online 中打开

You have four variables each (1x501) vectors. Your time variable is a (7x1) double, so doing anything with respect to that time vector is not going to work. You could get time from the position differences and the velocities, but I am lost as to what you want to do. Plotting ‘v_x’ and ‘v_y’ is straightforward and produces 5 straight lines.

I have no idea what you want to do, but I took a wild guess and came up with this:

D = load('Arsal15 node_property.mat');
np = D.node_property;
x = np.v_x;
y = np.v_y;
vx = np.vel_x;
vy = np.vel_y;
xp = gradient(x);                                   % X-Position Change
yp = gradient(y);                                   % Y-Position Change
vt = hypot(vx(:), vy(:));                           % Net Velocity
pt = hypot(xp, yp);                                 % Net Position Change
tv = pt(:)./vt(:);                                  % Differential Time
tc = cumsum(tv);                                    % Cumulative Time
figure(1)
plot3(x, y, tc, '-r')
hold on
quiver3(x(:), y(:), tc(:), xp(:), yp(:), tv(:), 1.5, 'LineWidth',1)
hold off
grid on
xlabel('X')
ylabel('Y')
zlabel('Time')
figure(2)
plot3(x, y, tc, '.r')
hold on
quiver3(x(:), y(:), tc(:), xp(:), yp(:), tv(:), 2.5, 'LineWidth',1)
hold off
grid on
xlabel('X')
ylabel('Y')
zlabel('Time')

Arsal15 2016-1-21

在 MATLAB Online 中打开

Thanks for your time and kind reply Star Strider.

Actually I want to do three things

Regarding time I can use interpolation like this so all index will be (1x51).

if true
node_property(nodeIndex).time = interp1(s_mobility.VS_NODE(nodeIndex).V_TIME,v_t);
end

1) .Getting data from the structure in a efficient way so that I use one loop index and I get data of all mobile nodes in their variable like x_position, y_position x_velocity, y_velocity using single for loop.

2). I want the position of mobile node at any instant of time like if I call a function

if true
  [x,y] = node_position(node_number,time_instant,direction);
end

it gives times position of that node at that time instant but also direction vector value.

3). I want to calculated distance of node1(x,y) with node2(x,y) I am using function

if true
  distance = findSqDistance(node1_X,node1_Y,node2_X,node2_Y);
end

but I am fail to pass array of (1x51) of x and y of node1 and node 2 to this function and get a result back in distance matrix which also a (1x51) so I m stuck. Actually i get puzzled in indexing.