To find values by using position vector

Xia
2015 3 18
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更新时间：2015 3 18
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Suppose matrix A=[1 3 5 7 9]. The position vector is known, which is, say, B=[ 3 4 ]. So the intended answer should be [ 5 7 ] which are elements at the 3rd and 4th places. Is there a function to achieve this? In fact the matrix A is high dimensional and there are many position vectors, and for loops seem not the most effective way...
Thanks in advance.

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the cyclist
the cyclist 2015-3-18

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answer = A(B)

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Xia
Xia 2015-3-18
Thank you so much. I must be too stupid to ignore the basic indexing. Thanks for your help!

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Guillaume
Guillaume 2015-3-18

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It's very basic matrix indexing:
A=[1 3 5 7 9];
B=[ 3 4 ];
C = A(B)
For N-d matrices, you may have to use sub2ind to go from coordinates to linear indices.

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Xia
Xia 2015-3-18
Thank you Guillaume. You are right it's really basic and I learned from you. Again thanks for your time my friend!

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