sum of dirac delta function

Hi,

I am trying to write a single sum of many dirac terms like dirac(x-1)+dirac(x-4)+dirac(x-7)+dirac(x-10) and so on. There is an increment of 3 in each sucessive term and it can go quite far like 200. Can we write a code that just sums all dirac terms like a series?

Thanks

Dharma

syms x t

y(x) = (dirac(x-1) + dirac(x-4)+................;

z = y(x)* exp(-4*(t-x));

Answer 1

[Paul]

syms d(x) t
d(x) = dirac(x);
t0 = 1:3:10; % a couple of terms for example
y(x) = sum(d(x-t0))

y(x) = 

Answer 2

[Chunru]

syms x t
y(x) = dirac(x-1);
for i=4:3:200
    y(x) = y(x) + dirac(x-i);
end
z = y(x)* exp(-4*(t-x));
y

y(x) = 

z

z = 

[Dharma Khatiwada]

Thank You.