Piece wise function without predefined intervals

Question

I want to make an .m file that represents a piece wise function and returns a vector with all the discrete values calculated.

To be a bit more clear, I want a function (which I have named Iapp and is time dependant, so Iapp(t)) that returns zero for the first 100s then returns 0.5 for 100-120s then again zero for 120-220s then 0.5+0.2 for 220-240s and that goes on.

I know a piece wise function can be defined using logical indexing, but my problem is that my time interval for which I want the function is not predefined. So I don't know how logical indexing could work...if the time interval is not a multiple of 120 it doesn't work.

I have tried the following:

function Vect_Iapp = Iapp_morceaux(tspan, h)
i = 1;
j = 1;
t = tspan(1):h:tspan(2);
while t(i) < tspan(2)         
    while(t(i)< (j*100 + (j-1)*20))
        Iapp(i) = 0;
        i = i + 1;
    end
    while (t(i)>j*100 && t(i) < j*100 + j*20)
        Iapp(i) = 0.5 + j*0.2;
        i = i + 1;
    end
    j = j + 1;
end    
Vect_Iapp = Iapp;
end

But the algorithm does not always work like it should. Any ideas as to how this function could be defined? Note that I would also like to be able to somehow give a scalar value for tspan and make the function return just a scalar value back.

Answer 1

This function?

x=linspace(0,600,1000);
y=Iapp(x);
plot(x,y)

function y=Iapp(t)
    r=mod(t,120);
    c=floor(t/120);
    VAL1=0;
    VAL2=0.5 + 0.2*c;
    y=VAL1.*(r<=100) + VAL2.*(r>100);
end