trapezoidalrule.m

a = 0; b = 4; c = -2; d = 2

n = 20;


h = (b - a)/n; k = (d - c)/n;
x= a:h:b; y=c:k:d;


totallist = zeros(  1, length(y) )

for yi = 1:length(y)
    total = 0
    for xi = 2:length(x)-1
        temp = x(xi)^2 - 3*y(yi)^2 + x(xi)*y(yi)^3;
        total = total + 2*temp;
    end
    firstLast = [1,length(x)];

    for i=1:length(firstLast)
        xelm = firstLast(i);
        temp = x(xelm)^2 - 3*y(yi)^2 + x(xelm)*y(yi)^3;
        total = total + temp;
    end
    total = total*h/2;

    totallist(yi) = total ;

end



stotal = 0
for yi = 2:length(totallist)-1
    temp = totallist(yi);
    stotal = stotal + 2*temp;
end
totalLength = length(totallist);

stotal = stotal + totallist(1) + totallist(totalLength);

stotal = stotal*h/2;