Assigning a variable to any value in a matrix

Hi,

I am having trouble on a project involving matrices.

An example with simplified but similar code:

Matrix = [0 1 4; 4 1 3];

for x = 1:10

   if x + y == 5

My goal is to have y be ANY value in the original matrix, so the if statement is true if x + ANY Matrix Value is equal to 5.

Is this possible without using an extra for loop?

Thanks!

Answer 1

[Star Strider]

You came close to answering it yourself. There is an any funciton.

Experiment with this to see if it does what you want:

Matrix = [0 1 4; 4 1 3];
y = Matrix;
for x = 1:10;
    logic = any(x + y == 5)
end

EDIT — To see the results of the comparison for different values of ‘x’, tweak the code to store the values, and display them in an array:

Matrix = [0 1 4; 4 1 3];
y = Matrix;
for x = 1:10;
    logic(x) = nnz(any(x + y == 5));
end
Result = [[1:10]', (logic > 0)']

Result =

       1     1
       2     1
       3     0
       4     1
       5     1
       6     0
       7     0
       8     0
       9     0
      10     0

Answer 2

[Jon]

Try this

for x = 1:10
   if sum(x + Matrix(:) == 5) > 0
      disp(x)
   end
end

[roram]

Is there a way to store the Matrix index that fulfilled the condition?

[dpb]

There are multiple possible locations...but, use logical array or find or the like--

>> x=1;  % define an example x
>> (x+Matrix==5)  % logical array
ans =
   0     0     1
   1     0     0
>> [i j]=find(x+Matrix==5);  % return locations
>> disp([i j])
   2     1
   1     3
>>

Again, need more detail on what your end result is to be to have any real definitive implementation suggestions.

Answer 3

[dpb]

Matrix = [0 1 4; 4 1 3];
for x = 1:10
  if any(x+Matrix(:)==5)
    ...

NB: use of : to treat array as a vector such that any will return a single result.

You could possibly eliminate the loop entirely depending on what the resulting operation is.