Hi, I wrote a very simple program for fourrow_dp.f90 but it doesn't work. I have attached the program. Could anyone give me some advice where I've made mistakes?

PROGRAM MAIN
IMPLICIT NONE
INTEGER i
COMPLEX(kind=8) data(1,1:512)
do 10 i=1,512,1
data(1,i)=1.0d0
10 continue
call fourrow_dp(data,1)
END

Thanks a lot!