cutting a matrix A into 3 pieces with respect to matrix B

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Mori
Mori 2015-7-17
编辑： Mori 2015-7-17
here we have :
A=[1 2 3 14 15 16 7 8]
B=[1 2 3]
we know location of B is over 14 15 16 of matrix A.
we need to get 3 different matrix as below:
c=[1 2 3]
d=[14 15 16]
e=[7 8]
whar are the commands? many thanks in advance
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Walter Roberson
Walter Roberson 2015-7-17
Is it known that those entries in B are bit-for-bit copies of the entries in A? Such as if A was indexed to produce B? Because when two floating point values are computed by even very very slightly different code, the results will not necessarily be equal due to floating point round-off. If the entries are not bit-for-bit copies then you will need to compare with a tolerance rather than compare for equality.
http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
Mori
Mori 2015-7-17
I can manage to get column 2 and 3 of A and B exactly equal, i.e. bit-for-bit copies. tried your answer but got error message. lets take into account that Columns 2 and 3 is equal in both matrix.

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Walter Roberson
Walter Roberson 2015-7-17
[tf, idx] = ismember(B, A, 'rows');
minidx = min(idx);
maxidx = max(idx);
c = A(1:minidx-1,:);
d = A(minidx:maxidx,:);
e = A(maxidx+1:end, :);
  2 个评论
Mori
Mori 2015-7-17
编辑：Mori 2015-7-17
just changed 'rows' to 'legacy' and it worked. Thank you
[tf, idx] = ismember(B, A, 'legacy');
minidx = min(idx);
maxidx = max(idx);
c = A(1:minidx-1,:);
d = A(minidx:maxidx,:);
e = A(maxidx+1:end, :);

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