diff --git a/brainpy/_src/math/event/csr_matmat.py b/brainpy/_src/math/event/csr_matmat.py
index 8cdc750b..da3902c8 100644
--- a/brainpy/_src/math/event/csr_matmat.py
+++ b/brainpy/_src/math/event/csr_matmat.py
@@ -234,33 +234,33 @@ def _event_csr_matmat_bool_homo(values: ti.types.ndarray(ndim=1),
 
 
 @ti.kernel
-def _event_csr_matmat_sum(values: ti.types.ndarray(ndim=1),
-                          col_indices: ti.types.ndarray(ndim=1),
-                          row_ptr: ti.types.ndarray(ndim=1),
-                          matrix: ti.types.ndarray(ndim=2),
-                          out: ti.types.ndarray(ndim=1)):
-  for row_i in ti.ndrange(out.shape[0]):
+def _event_csr_matmat_dw(dy: ti.types.ndarray(ndim=1),
+                         col_indices: ti.types.ndarray(ndim=1),
+                         row_ptr: ti.types.ndarray(ndim=1),
+                         matrix: ti.types.ndarray(ndim=2),
+                         dw: ti.types.ndarray(ndim=1)):
+  for row_i in ti.ndrange(dw.shape[0]):
     temp_sum = 0.
     for row_j in range(row_ptr[row_i], row_ptr[row_i + 1]):
       for col_k in range(matrix.shape[1]):
         if matrix[col_indices[row_j], col_k] != 0.:
-          temp_sum += values[row_j] * matrix[col_indices[row_j], col_k]
-    out[row_i] = temp_sum
+          temp_sum += dy[row_j] * matrix[col_indices[row_j], col_k]
+    dw[row_i] = temp_sum
 
 
 @ti.kernel
-def _event_csr_matmat_bool_sum(values: ti.types.ndarray(ndim=1),
-                               col_indices: ti.types.ndarray(ndim=1),
-                               row_ptr: ti.types.ndarray(ndim=1),
-                               matrix: ti.types.ndarray(ndim=2),
-                               out: ti.types.ndarray(ndim=1)):
-  for row_i in ti.ndrange(out.shape[0]):
+def _event_csr_matmat_bool_dw(dy: ti.types.ndarray(ndim=1),
+                              col_indices: ti.types.ndarray(ndim=1),
+                              row_ptr: ti.types.ndarray(ndim=1),
+                              matrix: ti.types.ndarray(ndim=2),
+                              dw: ti.types.ndarray(ndim=1)):
+  for row_i in ti.ndrange(dw.shape[0]):
     temp_sum = 0.
     for row_j in range(row_ptr[row_i], row_ptr[row_i + 1]):
       for col_k in range(matrix.shape[1]):
         if matrix[col_indices[row_j], col_k]:
-          temp_sum += values[row_j] * matrix[col_indices[row_j], col_k]
-    out[row_i] = temp_sum
+          temp_sum += dy[row_j] * matrix[col_indices[row_j], col_k]
+    dw[row_i] = temp_sum
 
 
 def _event_csr_matmat_jvp_values(val_dot, values, col_indices, row_ptr, matrix, *, outs, transpose, shape):
@@ -291,13 +291,11 @@ def _event_csr_matmat_transpose(
       else:  # heter
         matrix = jnp.asarray(matrix)
         if matrix.dtype == jnp.bool_:
-          prim = _event_csr_matmat_bool_sum
+          prim = _event_csr_matmat_bool_dw
         else:
-          prim = _event_csr_matmat_sum
+          prim = _event_csr_matmat_dw
         ct_data = prim(ct[0], indices, indptr, matrix,
                        out=jax.ShapeDtypeStruct((data.aval.shape[0], matrix.shape[1]), data.aval.dtype))[0]
-        # row, col = csr_to_coo(indices, indptr)
-        # ct_data = (ct[0][row] * matrix[col]).sum(1)
     return ct_data, indices, indptr, matrix
 
 
@@ -340,11 +338,11 @@ def _define_op(cpu_kernel, gpu_kernel):
 _event_csr_matmat_bool_homo_p = _define_op(cpu_kernel=_event_csr_matmat_bool_homo,
                                            gpu_kernel=_event_csr_matmat_bool_homo)
 
-_event_csr_matmat_sum_p = XLACustomOp(cpu_kernel=_event_csr_matmat_sum,
-                                      gpu_kernel=_event_csr_matmat_sum)
+_event_csr_matmat_dw_p = XLACustomOp(cpu_kernel=_event_csr_matmat_dw,
+                                     gpu_kernel=_event_csr_matmat_dw)
 
-_event_csr_matmat_bool_sum_p = XLACustomOp(cpu_kernel=_event_csr_matmat_bool_sum,
-                                           gpu_kernel=_event_csr_matmat_bool_sum)
+_event_csr_matmat_bool_dw_p = XLACustomOp(cpu_kernel=_event_csr_matmat_bool_dw,
+                                          gpu_kernel=_event_csr_matmat_bool_dw)
 
 # heter CUSPARSE
 _csr_matmat_cusparse_p = csr.csr_matmat_p