How to build a graph using stem for a given equation?

As I understand it, the program stumbles over calling the delta function and builds one point. How can I display the desired graph without making the code too heavy?

Main script:

a1=1.7;
b1=9;

subplot(221);
n1=0:20;
x1=a1*delta(n1-b1);
stem(n1, x1);

File delta function (its use is mandatory):

function [ d ] = delta( n )

if n == 0
    d = 1;
else
    d = 0;
end

end

Answer 1

[Voss]

Your delta function makes d a scalar. Instead d should be the same size as n, with value 1 where n is 0 and value 0 everywhere else. If you can modify the delta function, do it.

a1=1.7;
b1=9;

% subplot(221);
n1=0:20;
x1=a1*delta(n1-b1);
stem(n1, x1);

function d = delta( n )
d = zeros(size(n)); % initialize d to be an array of 0 the same size as n
d(n == 0) = 1;      % set d to 1 where n is 0
end

[Kirin]

Thank you a lot! I got 2 good answers but this one is pretty universal for writing file-functions!

[Voss]

You're welcome!

Answer 2

[Torsten]

Since your delta function does not support array inputs, you must use something like

x1=a1*arrayfun(@(n1)delta(n1-b1),n1)

instead of

x1=a1*delta(n1-b1);

[Kirin]

Thank you, I didn't know about this command!