% matlab code to plot data generated by ex1.gms
% fancier plot, with every 5th data point indicated.

% load data from ex1.dat into the matrix ex1
load ex1.dat

% use spconvert to create a matrix A, with ordinate (X axis) as first col,
% and the four abscissae as 2nd, 3rd, 4th, 5th columns.
A = spconvert(ex1);

% add the required shift to get x
x = 1990:1990+size(A,1)-1;

% make this Figure 1
figure(1);

% form reduced versions of the abscissae and ordinates, including only
% every 5th data point
xred = x(1:5:41);
Ared = A(1:5:41,:);

% plot each line twice - first a continuous line, then mark every 5th
% data point with an x, o or whatever.
hred = plot(x,A(:,1),'y-', ...
         x,A(:,2),'g-', ...
         x,A(:,3),'c-', ...
         x,A(:,4),'b-');

hold on;

plot(xred,Ared(:,1),'yo', ...
         xred,Ared(:,2),'gx', ...
         xred,Ared(:,3),'cd', ...
         xred,Ared(:,4),'b.');

% reduce te vector of handles so that hred points only to the solid lines
% (which are the ones we want to label in the legend).
% hred= h(1:2:7);

% fix the ranges on the X and Y axes
axis([x(1) x(41) 0 5]);
xlabel('Time'); ylabel('A');

% make a legend, "0" allows Matlab to choose its location 
legend(hred,'a','b','c','d',0);
title('Example 1b: Plot of GAMS data in Matlab');