code: function trmv (A, x, isLower) {
    var dot = blas1.dot;
    var n = A.shape[1];
    var i = 0;
    if (isLower) {
      for (i = n - 1; i >= 0; i--) {
        x.set(i, dot(A.pick(i, null).hi(i + 1), x.hi(i + 1)));
      }
    } else {
      for (i = 0; i < n; i++) {
        x.set(i, dot(A.pick(i, null).lo(i), x.lo(i)));
      }
    }
    return true;
  }
docs: Compute the product of an upper triangular matrix with a vector