function i=p1(x0,y0)

% Eliza Dubroff
% 4/24/97
% ps7#1
% to find the volumes using matlab

 t(1) = -0.77459667;
 t(2) = 0;
 t(3) = 0.77459667;
 
 w(1) = 0.55555555;
 w(2) = 0.88888889;
 w(3) = 0.55555555;
 i1=0;
 i=zeros(3,1);

for k=1:3,
	i1=0;
	y=(y0*(1+t(k)))/2;
	for j=1:3,
		x=(x0*(1+t(j)))/2;
		d=sand(x,y)+20;
		i1=i1+(d*w(j));
	end
	i(1,1)=i(1,1)+(i1*w(k));
end
i(1,1)=i(1,1)*x0*y0/4;

for k=1:3,
	i1=0;
	y=(y0*(1+t(k)))/2;
	for j=1:3,
		x=(x0*(1+t(j)))/2;
		d=clay(x,y)-sand(x,y);
		i1=i1+(d*w(j));
	end
	i(2,1)=i(2,1)+(i1*w(k));
end
i(2,1)=i(2,1)*x0*y0/4;

for k=1:3,
	i1=0;
	y=(y0*(1+t(k)))/2;
	for j=1:3,
		x=(x0*(1+t(j)))/2;
		d=top(x,y)-clay(x,y);
		i1=i1+(d*w(j));
	end
	i(3,1)=i(3,1)+(i1*w(k));
end
i(3,1)=i(3,1)*x0*y0/4;