how to find the index value

suppose i have on matrix A

 A=  2
     3
     5
     7
     8
     10

i have another matrix B

 B= 
   10    21
   20    11
   63    43
   23    12
   32    54
   78    45

now i wish to get the value from A 7 and B 23 12 through index value.

suppose 7 value store in A 4 location now i get the 4 location values from B

Answer 1

[James Tursa]

If you are given the value 7 and want to find it in A and then get the corresponding row in B, then you could do this:

x = find(A==7);
r = B(x,:);

If you don't care about storing the index itself, then you can just use logical indexing directly:

r = B(A==7,:);