center of matrix value

How can i find the center value of a matrix NxN, where N is odd number. After that, how can i change that number for another number

Answer 1

[David Hill]

a=(size(yourMatrix)+1)/2;
yourMatrix(a(1),a(2))=newNumber;

[Alejandro Alarcon]

thank you

Answer 2

[Tommy]

centerValue = A((N*N+1)/2);
A((N*N+1)/2) = newValue;

[Alejandro Alarcon]

thank you