Plot wind directions and speed of a day with quiver

I have given two vectors holding 24 hourly values for wind speed and direction.

I would like to use quiver to plot 24 arrows indicating speed and direction graphically.

I failed with my first tries:

clc; % Clear the command window.
close all; % Close all figures 
clear all; % Erase all existing variables.
workspace; % Make sure the workspace panel is showing.

% given vector of windspeeds througout a day (every h)
windspeeds = rand(1,24)

 % given vector of wind directions througout a day (every h)
 % the direction is noted in degrees ° from nord
 winddirections = randi([1 360],1,24)

 % create x/y grid 24x24 for one day
 [x,y] = meshgrid(1:24,1:24)

 % substract 90° to re-align north to the top
 u= mod(90 - winddirections, 360)
 v= mod(90 - winddirections, 360)

 % convert from degrees to fit the x/y matrix
 u=  cos(u) * pi/180
 v=  sin(u) * pi/180

 % put it on quiver
 quiver( cos(u) * pi/180, sin(u) * pi/180, x, y)

Current Result is

I do not yet know how to place these 24 arrows and how to calculate u,v to represent the direction at the given position (time of the day). The quiver doc is rather short. Any hints on how I could proceed.

Answer 1

[KSSV]

workspace; % Make sure the workspace panel is showing.
% given vector of windspeeds througout a day (every h)
windspeeds = rand(1,24) ;
 % given vector of wind directions througout a day (every h)
 % the direction is noted in degrees ° from nord
 winddirections = randi([1 360],1,24) ;
 % create x/y grid 24x24 for one day
 [x,y] = meshgrid(1:24,1:24) ;
 % substract 90° to re-align north to the top
 u= mod(90 - winddirections, 360) ;
 v= mod(90 - winddirections, 360) ;
 % convert from degrees to fit the x/y matrix
 u=  cos(u) * pi/180 ;
 v=  sin(u) * pi/180 ;
 [U,V] = meshgrid(u,v) ;
 % put it on quiver
 quiver( x,y,U,V)

[MathMaus]

Thanks. This helped me a lot to understand the way how quiver works. I now changed my approach and use a Rotation Matrix to rotate the initial vector into the right position. For that reason I have written a function which should take the components x,y, d,s %scaled initial vector pointing upwards as row-vectors. It would work fine for a single tuple of x,y,d,s but fails with row-vectors feet to the function.

    function [vR]=drawWindDirection(x, y, d, s)

eV = [x, y + s]; % Draw Upright Einheitsvektor at given Position

% Construct the rotation Matrix 
theta = d; 
R = [cosd(theta) -sind(theta); sind(theta) cosd(theta)];
% 
vR = eV * R;
%vR = eV .*R;
%vR =(R*eV.').';

end

I get the error: Error using * Inner matrix dimensions must agree.

vR = eV * R;

Of course the dimension of the arow vector and the rotation map are different. I'm sure this is another newby issue. How can I convince Matlab to calculate it, as i have learned it at School?

[KSSV]

Mention the input x,y,d,s so that we can check the code.