added update_select_rows to doc

1 files changed, 2 insertions, 0 deletions

diff --git a/nerv/doc/nerv_matrix.md b/nerv/doc/nerv_matrix.md
index 54bf440..b915dee 100644
--- a/nerv/doc/nerv_matrix.md
+++ b/nerv/doc/nerv_matrix.md
@@ -67,6 +67,8 @@ Copy the content of the __Matrix__ `self` to a __CuMatrix__ `a`.
 `idx` should be a row vector. This function copy the rows of `ma` to `self` according to `idx`, in other words, it assigns `ma[idx[i]]` to `self[i]`.
 * __void Matrix.copy_rows_fromd_by_idx(Matrix self, CuMatrix b, CuMatrix idx)__  
 `idx` needs to a row vector matrix, it stacks the rows of index `idx` of the __CuMatrix__ `b` and copies to `self`.
+* __void Matrix.update_select_rows(Matrix self, Matrix err, Matrix idx, double alpha, double beta)__  
+Update selected rows of `self`, i.e. `self[idx[i]] = self[idx[i]] * (1 - beta * alpha) + alpha * err[i]`.
 * __void Matrix.add(Matrix self, Matrix ma, Matrix mb, Element_type alpha, Element_type beta)__  
 It sets the content of __Matrix__ `self` to be `alpha * ma + beta * mb`.__Matrix__ `ma,mb,self` should be of the same size.
 * __void Matrix.mul(Matrix self, Matrix ma, Matrix mb, Element_type alpha, Element_type beta, [string ta, string tb])__