how to select a submatrix A from B based on indexes of matrix C intersected with D

Hello,

this is my situation: I have 3 matrices Numbers of size AxB contains values Dates of size AxB contains dates Dates2 of size Cx1 (C<=A, D<=B) contains dates

I would need to create matrix

Numbers2 of size CxB

that is a submatrix of Numbers, containing only the values whose associated date in matrix Dates is contained in matrix Dates2

thanks in advance

[Oleg Komarov]

Please, post an example: much easier to understand.