# matlab - number - Find given row in a matrix

## matlab table column names (3)

### EDIT:

gnovice's suggestion is even simpler than mine:

```
[~,indx]=ismember(X,M,'rows')
indx =
3
```

### FIRST SOLUTION:

You can easily do it using `find`

and `ismember`

. Here's an example:

```
M=magic(4); %#your matrix
M =
16 2 3 13
5 11 10 8
9 7 6 12
4 14 15 1
X=[9 7 6 12]; %#your row vector
find(ismember(M,X),1)
ans =
3
```

I have an m by n matrix in `MATLAB`

, say M. I have an n-element row vector, i.e. a one by n column matrix, say X.

I know X is a row somewhere in M. How can I find the index in M?

Another solution that returns a row index for each occurrence of X is

```
find(sum(abs(M-ones(rows(M),1)*X),2)==0)
```

Also, this solution can be easily adapted to find rows that are within threshold of X as follows (if numerical noise is an issue)

```
tolerance = 1e-16; %setting the desired tolerance
find(sum(abs(M-ones(rows(M),1)*X),2)<tolerance)
```

This is a non-loop version. It is only suitable, if M (your matrix) is not very large, ie. n and m are small. X is your row:

```
function ind = findRow(M,X)
tmp = M - repmat(X,size(M,1),1);
ind = find(tmp,1);
end
```

If M is too large, it might be faster, to iterate the rows of M and compare every row with your vector.

@Edit: renamed variables to match the names used in the question.