code: public void init( double diag[] ,
                        double off[],
                        int numCols ) {
          reset(numCols);
  
          this.diag = diag;
          this.off = off;
      }
docs: Sets up and declares internal data structures.
  
  @param diag Diagonal elements from tridiagonal matrix. Modified.
  @param off Off diagonal elements from tridiagonal matrix. Modified.
  @param numCols number of columns (and rows) in the matrix.