direct product of convex set

例句：

1. 1. Thefunction is the direct product of two convex sets.
   这个函数是两个凸集的直接乘积。
2. 2. In mathematics, a direct product of sets is acollection of subsets that are all subsets of the same set.
   在数学中，集合的直接乘积是指所有都是同一集合子集的集合的集合。
3. 3. The direct product of two vectorsis the result of multiplyingeach component by the other.
   两个向量的直接乘积是将每个分量乘以另一个的结果。