[linalg.layout.packed.obs] Introduce i and j earlier and use it in \expects

Author: jensmaurer

source/numerics.tex

@@ -11693,7 +11693,6 @@
 \end{itemdecl}
 
 \begin{itemdescr}
-
 \pnum
 \constraints
 \begin{itemize}
@@ -11707,16 +11706,18 @@
 \tcode{is_nothrow_constructible_v<index_type, Index1>} is \tcode{true}.
 \end{itemize}
 
+\pnum
+Let \tcode{i} be \tcode{extents_type::\exposid{index-cast}(ind0)}, and
+let \tcode{j} be \tcode{extents_type::\exposid{index-cast}(ind1)}.
+
 \pnum
 \expects
-\tcode{extents_type::\exposid{index-cast}(ind0), extents_type::\exposid{index-cast}(ind1)}
+\tcode{i, j}
 is a multidimensional index in \exposid{extents_}\iref{mdspan.overview}.
 
 \pnum
 \returns
-Let \tcode{N} be \tcode{\exposid{extents_}.extent(0)},
-let \tcode{i} be \tcode{extents_type::\exposid{index-cast}(ind0)}, and
-let \tcode{j} be \tcode{extents_type::\exposid{index-cast}(ind1)}.
+Let \tcode{N} be \tcode{\exposid{extents_}.extent(0)}.
 Then
 \begin{itemize}
 \item