% GRAB = Growth, Replacement and Burn Matrices
%
% function [G,R,B] = grab(t, c, growth, replace, burn)
%
% 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] = grab(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
count = 1;
for Pg = 1 : N,
    G(count,Pg) = 1 - growth(I,Pg);
    G(count+1,Pg) = growth(I,Pg);
    count = count + 1;
end
G(N+1,N+1) = 1;

% Fill in replacement matrix
count = 1;
for Pri = 1 : l,
    for Prj = 1 : l,
        if Pri == 1
            R(Pri,Prj) = replace(J,Prj);
        else
            R(Pri,Prj) = 0;
        end
    end
end

% Fill in burn matrix
count = 1;
for Pbi = 1 : n,
    for Pbj = 1 : n,
        if Pbi == Pbj
            B(Pbi,Pbj) = burn(K,Pbj);
        else
            B(Pbi,Pbj) = 0;
        end
    end
end