Need help solivng euler method code

We had to create a matlab function based off of the euler method from calculus. I am having an issue getting my code to work. The code just outputs an array of 1001 zeros instead of the calculated values. Can I get help fixing my euler method code?

Inputs for function >>>>>>>>> t0=0, tf=f, h=0.005, y0=10

The differential equation is >>>>> dy/dt = -0.1 * y

function [y] = euler1(t0,tf,dt,y0)
%euler: utilizes the euler method to solve a differential equation
%   Input: 
%       h ........ step size
%       xi ....... starting position
%       xf ....... ending position
%       y0 ...... Intitial y value
%   Output:
%       y ........ function value

x = (t0:dt:tf); 
y = zeros(size(x));
n = numel(y0);

for i=1:n-1
    f = -0.1 *y;
    y(i+1) = y(i) + dt * f;
end
end

Answer 1

[James Tursa]

This

n = numel(y0);

needs to be this instead

n = numel(x); % number of independent variable values

Then you need to initialize your output array with the initial value. So add this line just before the for-loop:

y(1) = y0; % initial y value goes in the 1st spot

Then inside your for-loop, this line

f = -0.1 *y; % this sets f to be -0.1 times the ENTIRE y array, not what we want

needs to be indexed, like this

f = -0.1 *y(i); % this sets f to be -0.1 times the current value of y(i) only