Runge-Kutta 2 i matlab!

clear all

x(1)=0;
y(1)=1;

%[a,b] is the interval at which we are looking
a = 0;
b = 1;
h = 0.01;

%N is the total number of steps in our interval, and h is the step size

N = (b-a)/h;


%2nd order RK, with coefficient values assigned according Heun's method:

for n=1:(N-1);

    k1 = -x(n)*y(n)*h;
    k2 = -(x(n)+h)*(y(n)+h);
    y(n+1) = y(n) + (1/2*k1 + 1/2*k2)*h;
    
end

plot(x,y,x,exp(-x.^2./2).*1);

??? Attempted to access x(2); index out of bounds because numel(x)=1.

Error in ==> E12 at 21
    k1 = -x(n)*y(n)*h;

x = zeros(1,N);
y = zeros(1,N);

clear all
close all

x(1)=0;
y(1)=1;

%[a,b] is the interval at which we are looking
a = 0;
b = 1;

%N is the total number of steps in our interval, and h is the step size
h = input('Step size h=')
%h = 0.001;
N = 1/h;

%memory is allocated -- THIS DOESN'T WORK, DON'T KNOW WHY 
%x = zeros(1,N);
%y = zeros(1,N);

%2nd order RK, with coefficient values assigned according Heun's method:

for n=1:(N-1);

    x(n+1) = x(n) + h;
    k1 = -x(n)*y(n);
    k2 = -(x(n)+h)*(y(n)+h);
    y(n+1) = y(n) + (1/2*k1 + 1/2*k2)*h;
    
end

%the result is plotted, along with the exact solution for comparison

plot(x,y,'r')
hold on
plot(x,exp(-x.^2./2),'b')