diff --git a/docs/source/mat4.rst b/docs/source/mat4.rst
index 30f48fe..294f8f4 100644
--- a/docs/source/mat4.rst
+++ b/docs/source/mat4.rst
@@ -45,6 +45,7 @@ Functions:
 #. :c:func:`glm_mat4_inv_fast`
 #. :c:func:`glm_mat4_swap_col`
 #. :c:func:`glm_mat4_swap_row`
+#. :c:func:`glm_mat4_rmc`
 
 Functions documentation
 ~~~~~~~~~~~~~~~~~~~~~~~
@@ -270,3 +271,20 @@ Functions documentation
       | *[in, out]*  **mat**   matrix
       | *[in]*       **row1**  row1
       | *[in]*       **row2**  row2
+
+.. c:function:: float  glm_mat4_rmc(vec4 r, mat4 m, vec4 c)
+
+    | **rmc** stands for **Row** * **Matrix** * **Column**
+
+    | helper for  R (row vector) * M (matrix) * C (column vector)
+
+    | the result is scalar because S * M = Matrix1x4 (row vector),
+    | then Matrix1x4 * Vec4 (column vector) = Matrix1x1 (Scalar)
+
+    Parameters:
+      | *[in]*  **r**  row vector or matrix1x4
+      | *[in]*  **m**  matrix4x4
+      | *[in]*  **c**  column vector or matrix4x1
+
+    Returns:
+        scalar value e.g. Matrix1x1
diff --git a/docs/source/vec4.rst b/docs/source/vec4.rst
index 5bb1ac7..f497868 100644
--- a/docs/source/vec4.rst
+++ b/docs/source/vec4.rst
@@ -58,11 +58,7 @@ Functions:
 #. :c:func:`glm_vec4_minv`
 #. :c:func:`glm_vec4_clamp`
 #. :c:func:`glm_vec4_lerp`
-#. :c:func:`glm_vec4_isnan`
-#. :c:func:`glm_vec4_isinf`
-#. :c:func:`glm_vec4_isvalid`
-#. :c:func:`glm_vec4_sign`
-#. :c:func:`glm_vec4_sqrt`
+#. :c:func:`glm_vec4_cubic`
 
 Functions documentation
 ~~~~~~~~~~~~~~~~~~~~~~~
@@ -401,3 +397,11 @@ Functions documentation
       | *[in]*  **to**     to value
       | *[in]*  **t**      interpolant (amount) clamped between 0 and 1
       | *[out]* **dest**   destination
+
+.. c:function:: void  glm_vec4_cubic(float s, vec4 dest)
+
+    helper to fill vec4 as [S^3, S^2, S, 1]
+
+    Parameters:
+      | *[in]*  **s**      parameter
+      | *[out]* **dest**   destination
diff --git a/include/cglm/call/mat4.h b/include/cglm/call/mat4.h
index 7e76f73..54fbcbe 100644
--- a/include/cglm/call/mat4.h
+++ b/include/cglm/call/mat4.h
@@ -113,6 +113,10 @@ CGLM_EXPORT
 void
 glmc_mat4_swap_row(mat4 mat, int row1, int row2);
 
+CGLM_EXPORT
+float
+glmc_mat4_rmc(vec4 r, mat4 m, vec4 c);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/include/cglm/mat4.h b/include/cglm/mat4.h
index 56c6de3..35d4117 100644
--- a/include/cglm/mat4.h
+++ b/include/cglm/mat4.h
@@ -677,4 +677,26 @@ glm_mat4_swap_row(mat4 mat, int row1, int row2) {
   mat[3][row2] = tmp[3];
 }
 
+/*!
+ * @brief helper for  R (row vector) * M (matrix) * C (column vector)
+ *
+ * rmc stands for Row * Matrix * Column
+ *
+ * the result is scalar because S * M = Matrix1x4 (row vector),
+ * then Matrix1x4 * Vec4 (column vector) = Matrix1x1 (Scalar)
+ *
+ * @param[in]  r   row vector or matrix1x4
+ * @param[in]  m   matrix4x4
+ * @param[in]  c   column vector or matrix4x1
+ *
+ * @return scalar value e.g. B(s)
+ */
+CGLM_INLINE
+float
+glm_mat4_rmc(vec4 r, mat4 m, vec4 c) {
+  vec4 tmp;
+  glm_mat4_mulv(m, r, tmp);
+  return glm_vec4_dot(c, tmp);
+}
+
 #endif /* cglm_mat_h */
diff --git a/src/mat4.c b/src/mat4.c
index b62420e..c648a6e 100644
--- a/src/mat4.c
+++ b/src/mat4.c
@@ -151,3 +151,9 @@ void
 glmc_mat4_swap_row(mat4 mat, int row1, int row2) {
   glm_mat4_swap_row(mat, row1, row2);
 }
+
+CGLM_EXPORT
+float
+glmc_mat4_rmc(vec4 r, mat4 m, vec4 c) {
+  return glm_mat4_rmc(r, m, c);
+}