021. pack selects elements

topic: Arrays

pack.f90 | | |

integer :: v(3) = [1, -4, 9]

print *, pack(v, v > 0)  ! 1 9 -- keep values > 0
print *, count(v > 0)    ! 2   -- count values > 0
print *, size(v)         ! 3
print *, sum(v)          ! 6
print *, sum(v, v > 0)   ! 10  -- `sum` has optional mask
print *, sum(pack(v, v > 0))  ! 10

end

Output1

           1           9
           2
           3
           6
          10
          10

---

Pack selects elements

integer :: v(3) = [1,-4,9]
print*,pack(v,v>0) ! 1 9 -- keep values > 0
print*,count(v>0) ! 2 -- count values > 0
print*,size(v) ! 3
print*,sum(v) ! 6
print*,sum(v,v>0) ! 10 -- sum has optional mask
print*,sum(pack(v,v>0)) ! 10
end

— FortranTip (@fortrantip) December 19, 2021

---

1

Compiled using GNU Fortran (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0 with no flags