std::extents<IndexType,Extents...>::fwd-prod-of-extents
Min standard notice:
Returns the product of the sizes of extents with index less than i. The behavior is undefined if i <= rank() is false.
# Declarations
constexpr std::size_t /*fwd-prod-of-extents*/( rank_type i ) const noexcept;
(since C++23) (exposition only*)
# Parameters
i: The end index of the range of extents to be multiplied together.
# Return value
If i > 0 is true, return the product of extent(k) for all k in range [0,i), otherwise 1.