code: public static boolean isSkewSymmetric(DMatrixRMaj A , double tol ){
          if( A.numCols != A.numRows )
              return false;
  
          for( int i = 0; i < A.numRows; i++ ) {
              for( int j = 0; j < i; j++ ) {
                  double a = A.get(i,j);
                  double b = A.get(j,i);
  
                  double diff = Math.abs(a+b);
  
                  if( !(diff <= tol) ) {
                      return false;
                  }
              }
          }
          return true;
      }
docs: <p>
  Checks to see if a matrix is skew symmetric with in tolerance:<br>
  <br>
  -A = A<sup>T</sup><br>
  or<br>
  |a<sub>ij</sub> + a<sub>ji</sub>| &le; tol
  </p>
  
  @param A The matrix being tested.
  @param tol Tolerance for being skew symmetric.
  @return True if it is skew symmetric and false if it is not.