docs: public static void addIdentity(DMatrix1Row A , DMatrix1Row B , double alpha )
      {
          if( A.numCols != A.numRows )
              throw new IllegalArgumentException("A must be square");
          if( B.numCols != A.numCols || B.numRows != A.numRows )
              throw new IllegalArgumentException("B must be the same shape as A");
  
          int n = A.numCols;
  
          int index = 0;
          for( int i = 0; i < n; i++ ) {
              for( int j = 0; j < n; j++ , index++) {
                  if( i == j ) {
                      B.set( index , A.get(index) + alpha);
                  } else {
                      B.set( index , A.get(index) );
                  }
              }
          }
      }