doc change

1 files changed, 18 insertions, 5 deletions

diff --git a/doc/nerv_matrix.md b/doc/nerv_matrix.md
index c710ac8..097a2ed 100644
--- a/doc/nerv_matrix.md
+++ b/doc/nerv_matrix.md
@@ -3,12 +3,12 @@ Part of the [Nerv](../README.md) toolkit.
 
 ##Description##
 ###Underlying structure###
-In the begining is could be useful to know something about the underlying structure of a __Nerv__ matrix.  
+In the begining is could be useful to know something about the underlying structure of a __Nerv__ matrix. Please keep in mind that matrice in __Nerv__ is row-major.  
 Every matrix object is a encapsulation of a C struct that describes the attributes of this matrix.  
 ```
 typedef struct Matrix {
     size_t stride;              /* size of a row */
-    long ncol, nrow, nmax;    /* dimension of the matrix */
+    long ncol, nrow, nmax;    /* dimension of the matrix, nmax is simply nrow * ncol */
     union {
         float *f;
         double *d;
@@ -18,7 +18,7 @@ typedef struct Matrix {
 } Matrix;
 ```
 It is worth mentioning that that `data_ref` is a counter which counts the number of references to its memory space, mind that it will also be increased when a row of the matrix is referenced(`col = m[2]`). A __Nerv__ matrix will deallocate its space when this counter is decreased to zero.   
-Also note that all assigning operation in __Nerv__ is reference copy, you can use `copy_tod` or `copy_toh` method to copy value.
+Also note that all assigning operation in __Nerv__ is reference copy, you can use `copy_tod` or `copy_toh` method to copy value. Also, row assigning operations like `m1[2]=m2[3]` is forbidden in __Nerv__.
 
 ###Class hierarchy###
 The class hierarchy of the matrix classes can be clearly observed in `matrix/init.c`.   
@@ -27,6 +27,19 @@ Finally, there is __Nerv.CuMatrixFloat__, __Nerv.CuMatrixDouble__, inheriting __
 
 ##Methods##
 Mind that usually a matrix object can only do calculation with matrix of its own type(a __Nerv.CuMatrixFloat__ matrix can only do add operation with a __Nerv.CuMatrixFloat__).  
-In the methods description below, __Matrix__ could be __Nerv.CuMatrixFloat__, __Nerv.CuMatrixDouble__, __Nerv.MMatrixFloat__ or __Nerv.MMatrixDouble__.   
+In the methods description below, __Matrix__ could be __Nerv.CuMatrixFloat__, __Nerv.CuMatrixDouble__, __Nerv.MMatrixFloat__ or __Nerv.MMatrixDouble__. __Element_type__ could be `float` or `double`, respectively.    
 * __Matrix = Matrix(int nrow, int ncol)__  
-Returns a __Matrix__ object of `nrow` rows and `ncol` columns.
\ No newline at end of file
+Returns a __Matrix__ object of `nrow` rows and `ncol` columns.
+* __Element_type = Matrix.get_elem(Matrix self, int index)__  
+Returns the element value at the specific index(treating the matrix as a vector). The index should be less than `nmax` of the matrix.
+* __void Matrix.set_elem(Matrix self, int index, Element_type v)__  
+Set the value at `index` to be `v`.
+* __int Matrix.ncol(Matrix self)__  
+Get `ncol`, the number of columns.
+* __int Matrix.nrow(Matrix self)__  
+Get `nrow`, the number of rows.
+* __int Matrix.get_dataref_value(Matrix self)__  
+Returns the value(not a pointer) of space the `data_ref` pointer pointed to. This function is mainly for debugging.  
+* __Matrix/Element\_type, boolean Matrix.\_\_index\_\_(Matrix self, int index)__  
+If the matrix has more than one row, will return the row at `index` as a __Matrix__ . Otherwise it will return the value at `index`.
+* __boolean Matrix.\_\_newindex\_\_(Matrix self, int )__
\ No newline at end of file