Need help with debugging

Hey all, below is my coding which does fuzzy operation (addition, subtraction, multiplication, division)

My issue is that the upper limit after multiplying is completely different from what it should be (subplot 2,5,4 part) anyone have an idea why?

I dont know how I can have just that one part go wrong when the other operations work just fine.. Help!

 clear
clc
x = -10:0.1:10;
f1 = trapmf(x,[-2 0 0 4]);
f2 = trapmf(x,[-1 3 3 5]);
%f2 = gaussmf(x,[2,5])
f1print = roundn(f1,-2);
f2print = roundn(f2,-2);
kvals = 0.05:0.05:1;

 for kidx = 1 : length(kvals)

    k = kvals(kidx);
    index1 = find(abs(f1print-k)<10^-3)
    Xidx1{kidx} = x(index1);
    Xidx1{20} = [0 0];
    index2 = find(abs(f2print-k)<10^-3);
    Xidx2{kidx} = x(index2);
    Xidx2{20} = [0 0];

    A(kidx) = Xidx1{kidx}(1);
    B(kidx) = Xidx1{kidx}(2);
    C(kidx) = Xidx2{kidx}(1);
    D(kidx) = Xidx2{kidx}(2);

 end

 %Multiplication
E = [A.*C; A.*D ;B.*C ;C.*D ];
F = min(E);
G = -F;
Z = max(E);
%Division
H = [A./C;A./D;B./C;B./D];
I = min(H);
J = max(H);

 subplot(2,5,1)
plot(x,f1)
title('1');
 subplot(2,5,6)
plot(x,f2)
title('2');

 subplot(2,5,2)
plot(A+C,kvals,B+D,kvals)
title('1 + 2');
axis([-2 8 0.05 0.95]);
 subplot(2,5,7)
plot(x,fuzarith(x,f1,f2,'sum'))
title('1 + 2 Built-In');
axis([-2 8 0.05 0.95]);

 subplot(2,5,3)
plot(A-D,kvals,B-C,kvals)
title('1 - 2');
axis([-9 3 0.05 0.95]);
 subplot(2,5,8)
plot(x,fuzarith(x,f1,f2,'sub'))
title('1 - 2 Built-In');
axis([-9 3 0.05 0.95]);

 subplot(2,5,4)
plot(F,kvals, Z,kvals)
title('1 * 2');
axis([-10 10 0.05 0.95]);

 subplot(2,5,9)
plot(x,fuzarith(x,f1,f2,'prod'));
title('1 * 2 Built-In');
axis([-10 10 0.05 0.95]);

 subplot(2,5,5)
plot(I,kvals,J,kvals)
title('1 / 2');
axis([-2 2 0.05 0.95]);
 subplot(2,5,10)
plot(x,fuzarith(x,f1,f2,'div'));
title('1 / 2 Built-In');
axis([-2 2 0.05 0.95]);