M = 9000;
N = 1700;
A = randn(M,N);
A = A>0.0;


%%%%%%%%%%%%%%%%%%%% 方法1 %%%%%%%%%%%
fprintf('\n1: ');
tic
b = find(A>0);
c = mod(b,M);
x1 = sum(c)+numel(find(c==0))*M;
y1 = sum(ceil(b./double(M)));
n1 = numel(b);

toc

%%%%%%%%%%%%%%%%%%%% 方法2 %%%%%%%%%%%
fprintf('2: ');
tic
sx = 0;
sy = 0;
n2 = 0;

for i = 1:M
	for j = 1:N
		if A(i,j) > 0
			sx = sx + i;
			sy = sy + j;
			n2 = n2 + 1;
		end
	end
end
x2 = sx;
y2 = sy;
toc

%%%%%%%%%%%%%%%%%%%% 方法3 %%%%%%%%%%%
fprintf('3: ');
tic
sx = 0;
sy = 0;

for j = 1:N
	c = find(A(:,j)>0);
	sy = sy + numel(c)*j;
	sx = sx + sum(c);
end
x3 = sx;
y3 = sy;
toc


fprintf('(%d,%d,%d),(%d,%d,%d),(%d,%d)\n',x1,y1,n1,x2,y2,n2,x3,y3);