how to generate n samples from a line segment using Matlab

Given n samples of 100,how do we generate these random samples in the line segment below using matlab

line_segement:

x between -1 and 1, y=2

If you want to generate n random samples between to given limit (in your question -1 and 1), you can use the function rand.

Here an example:

% Define minimum x value
x_min=-1
% Define maximum x value
x_max=1
% Define the number of sample to be generated
n_sample=100
% Generate the samples
x_samples = sort(x_min + (x_max-x_min).*rand(n_sample,1))

In the example, the sort function is called to sort the values in order to have an ascendent series.

x_min and (x_max-x_min) are used to "shift" the series of random values so that it belongs to the desired interval (in this case -1 1), since rand returns random number on an open interval (0,1).

If you want to have a XY matrix composed by the random samples and the defined constant y value (2):

y_val=2;
xy=[x_samples ones(length(x_samples),1)*y_val]

plot([x_min x_max],[y_val y_val],'linewidth',2)
hold on
plot(xy(:,1),xy(:,2),'d','markerfacecolor','r')
grid on
legend({'xy segment','random samples'})

(in the picture, only 20 samples have been plot to make it more clear)

Hope this helps.