plot_dir.m

function [h1] = plot_dir (vX, vY,color_dir)
%function [h1, h2] = plot_dir (vX, vY)
%Plotting x-y variables with direction indicating vector to the next element.
%Example
%   vX = linspace(0,2*pi, 10)';
%   vY = sin (vX);
%   plot_dir(vX, vY);
rMag = 1;%0.5;
% Length of vector
lenTime = length(vX);
% Indices of tails of arrows
vSelect0 = 1:(lenTime-1);
% Indices of tails of arrows
vSelect1 = vSelect0 + 1;
% X coordinates of tails of arrows
vXQ0 = vX(vSelect0, 1);
% Y coordinates of tails of arrows
vYQ0 = vY(vSelect0, 1);
% X coordinates of heads of arrows
vXQ1 = vX(vSelect1, 1);
% Y coordinates of heads of arrows
vYQ1 = vY(vSelect1, 1);
% vector difference between heads & tails
vPx = (vXQ1 - vXQ0) * rMag;
vPy = (vYQ1 - vYQ0) * rMag;
% % make plot 
% h1 = plot (vX, vY, [color_dir 'o-'],'linewidth',2); hold on;
% % add arrows 
% h2 = quiver (vXQ0,vYQ0, vPx, vPy, 0, color_dir,'MaxHeadSize',0.1,'linewidth',2); grid on; hold off
% make plot 
h1 = plot (vX, vY, 'o-','color', color_dir,'linewidth',1); hold on;
% add arrows 
%h2 = quiver (vXQ0,vYQ0, vPx, vPy, 0,'color', color_dir,'MaxHeadSize',0.25,'linewidth',1.5); 
grid on; hold off
ax = gca;
ax.GridLineStyle = '-';
ax.GridColor = 'k';
ax.GridAlpha = 1; % maximum line opacity
% axis equal