how to create triangular wave form in two dimension as a fringe pattern in matrix form ?

i want to represent triangular wave form in to fringe pattern like sinusoidal fringe pattern in matrix form, how to do? code for triangular wave form is given below

%triangular waveform(1)
n=15;
t=0:n;
y=(-1).^t; 
plot(t,y);
ylabel ('Amplitude');
xlabel ('Time Index');
TITLE ('Triangular waveform');