When a=[1, 2, 3] and b=[1, 2, 3, 3, 2, 1], yc = conv(reverse(a), b) returns

[3, 8 14, 17, 15, 10, 4, 1],

and yx = xcorr(a, b) returns

[1, 4, 10, 15, 17, 14, 8, 3, 0, 0, 0].

Shouldn’t yx be same as yc?

yx1 = xcorr(b, a) returns

[0, 0, 0, 3, 8 14, 17, 15, 10, 4, 1]. yx1 seems to be right if it means cross-correlation (a, b) except the leading zeros. Where do these zeros come from?