% FGRAB = Fast Growth, Replacement and Burn Matrices
% 
% function [G,R,B] = fgrab(time, control, growth, replace, death)
% 
% This function grabs the growth, replacement and death information for a given year
%   time = year you are considering
%   control = frequency of control burning in years
%   growth = the matrix which contains the growth information for the tree population
%   replace = the matrix which contains the reproduction information for the tree population
%   death = the matrix which contains the death information for the tree population
%

function [G,R,B] = fgrab(t, c, growth, replace, burn)

% Find sizes of matrices
[M,N] = size(growth);
[L,l] = size(replace);
[m,n] = size(burn);

% Check matrice lengths
if N ~= l - 1 | n ~= l,
    error = 'fgrab: Matricies are not of the same length.  N = L - 1 and n = L'
    N
    n
    l
    break;
end

% Determine which year in the cycle the growth and replacement matrices will be for
%
% For growth matrix
if mod(t,c) >= M
    I = M;
else
    I = mod(t,c) + 1;
end

% For replacement matrix
if mod(t,c) >= L
    J = L;
else
    J = mod(t,c) + 1;
end

% For burn/death matrix
if mod(t,c) >= m
    K = m;
else
    K = mod(t,c) + 1;
end    

% Fill in growth matrix using matrix mutliplication
g = growth(I,:);
G = diag([1-g,1]) + [[zeros(1,length(g+1));diag(g)],zeros(length(g)+1,1)];

% Fill in replacement matrix
R = zeros(l,l);
R(1,:) = replace(J,:);

% Fill in burn matrix
B = diag(burn(K,:));