Searching in a sorted 2D matrix

//I think I read this in a book somewhere, but it seems like a very elegant solution. Typing from memory, so this may or may not work as-is.

public boolean findElem(int matrix[][], int elem)
{
int rows = matrix.length;
int cols = matrix[0].length;
int start = 0;
int end = rows*cols - 1;

while(start<= end)
 {
  int mid = start + (end-start)/2;
  int row = mid/cols;
  int col = mid% cols;
  int curElem = matrix[row][col];
  if(curElem == elem)
     return true;
  if(curElem > elem)
     end = mid - 1;
  else
     start = mid + 1;
 }
return false;
}