Fixed docs wording and made pure function

Author: ghbrown

doc/specs/stdlib_linalg.md

@@ -191,7 +191,7 @@ Computes the outer product of two vectors
 
 ### Return value
 
-Returns a rank-2 array equal to `u v^T` (assuming `u, v` are column vectors). The shape of the returned array is `[size(u), size(v)]`.
+Returns a rank-2 array equal to `u v^T` (where `u, v` are considered column vectors). The shape of the returned array is `[size(u), size(v)]`.
 
 ### Example
 

src/stdlib_linalg.fypp

@@ -73,7 +73,7 @@ module stdlib_linalg
     !! Computes the outer product of two vectors, returning a rank-2 array
     !! ([Specification](../page/specs/stdlib_linalg.html#description_3))
     #:for k1, t1 in RCI_KINDS_TYPES
-      module function outer_product_${t1[0]}$${k1}$(u, v) result(res)
+      pure module function outer_product_${t1[0]}$${k1}$(u, v) result(res)
         ${t1}$, intent(in) :: u(:), v(:)
         ${t1}$ :: res(size(u),size(v))
       end function outer_product_${t1[0]}$${k1}$

src/stdlib_linalg_outer_product.fypp

@@ -7,7 +7,7 @@ submodule (stdlib_linalg) stdlib_linalg_outer_product
 contains
 
   #:for k1, t1 in RCI_KINDS_TYPES
-    module function outer_product_${t1[0]}$${k1}$(u, v) result(res)
+    pure module function outer_product_${t1[0]}$${k1}$(u, v) result(res)
       ${t1}$, intent(in) :: u(:), v(:)
       ${t1}$ :: res(size(u),size(v))
       integer :: col