function estimate = numint(f,n,a,b,method)
% Thanks to Mary Begay for providing this template.
% Input Notes:
% f: @(x) FUNCTION	=> for example @(x) x^2
% a: lower limit	=> number
% b: upper limit 	=> number
% n: Interval       => number
% method:           => string, 'lhs' or 'rhs'

% Checking method input is a string
rule = isstr(method);
if rule == 0
    display('Error: Method input must be a string')
end
%% Left Hand Sum
if method == 'lhs'
    
    h = (b-a)/n;
    % Creating a loop for the sum of f(xj) from j = 0 to n-1
    sum = 0;
    for j = 0:1:n-1
        xj = a+j*h;
        yj = feval(f,xj);
        sum = sum+yj;
    end
    estimate = h*sum;
    
    %% Right Hand Sum
elseif method == 'rhs'
    
    h = (b-a)/n;
    % Creating a loop for the sum of f(xj) from j = 1 to n
    sum = 0;
    for j = 1:1:n
        xj = a+j*h;
        yj = feval(f,xj);
        sum = sum+yj;
    end
    estimate = h*sum;
    
elseif true
    fprintf('Error: method ');
    fprintf(method)
    fprintf(' has not been programmed yet.\n');
    estimate = 0;
end
end