finding coordinates or locations in matrix?

Hi, I am trying to find a way of extracting the coordinates of the values that are larger than 20 in a magic(5) matrix.

I would like to have the coordinates specified as 3,5 instead of 15 and so on,, is that possible?

Thanks

>> r=magic(5)

r =

    17    24     1     8    15
    23     5     7    14    16
     4     6    13    20    22
    10    12    19    21     3
    11    18    25     2     9

>> b=r>20

b =

     0     1     0     0     0
     1     0     0     0     0
     0     0     0     0     1
     0     0     0     1     0
     0     0     1     0     0

>> find(b==1)

ans =

     2
     6
    15
    19
    23

>>

Answer 1

[Matt Tearle]

[row,col] = find(...)

[Andrei Bobrov]

[row,col] = find(r>20)

[Sara Ismail-Sutton]

Hi , sorry to re-bump an old thread but perhaps better than starting a new one. I'm doing the same thing I have a matrix X which is all zeros and 6x6 except X(1,6) and X(6,1) which are equal to 1. when i do

[row,col]=find(X==1)

or

[row,col]=find(X>0)

I'm getting the error message:

"Insufficient number of outputs from right hand side of equal sign to satisfy assignment."

Many thanks !!

[Image Analyst]

Not what anyone else gets:

X = zeros(6, 6);
X(6, 1) = 1;
X(1, 6) = 1
[row, col] = find(X == 1)
[row, col] = find(X > 0)

The result is not an error. It is:

X =

0 0 0 0 0 1

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

0 0 0 0 0 0

1 0 0 0 0 0

row =

6

1

col =

1

6

row =

6

1

col =

1

6

[Sara]

Hi, how to find the coordnates for 3D meshgrid as following

x = linspace(-10,10,50);
[X,Y,Z]=meshgrid(x,x,x);