Transferring value into a do loop

[clergy1122]

I'm really a novice. I wrote a small utility to calculate averages of numbers which it reads from a file. After reading I discover that it does not send the same values to the next loop. Unfortunately it works for a simple data set but not for my problem which has large data.
Here is the program;

Program Average
implicit none

integer::max
parameter(max=50)
integer::i,i1,j,N,tmp,N1,Num
real::K1,K2,K3,K4

integer,dimension(max)::Tag
real,dimension(max)::Asv,k,ar3,vol,ln,Asl,Avol,Aln

open(unit=1,file="ave2")
read(1,*)N
!write(,*)N
do i=1,N
read(1,*)Tag(i),k(i),ar3(i),vol(i),ln(i)
K1=k(i);k2=ar3(i);K3=vol(i);K4=ln(i)
enddo

Num=0
do i=1,N
K1 = k(i)
K2 = ar3(i)
K3 = vol(i)
K4 = ln(i)
N1=1
print*,K1,K2,K3,K4
print*,k(i),ar3(i),vol(i),ln(i)
do j=i+1,N
if(Tag(i).EQ.Tag(j))then
N1=N1+1
K1=K1+k(j);K2=K2+ar3(j);K3=K3+vol(j)
K4=K4+ln(j)
k(j)=0
ar3(j)=0
vol(j)=0
ln(j)=0
else
K1=K1
K2=K2
K3=K3
K4=K4
endif
enddo

Asl(i)=K1/N1
Asv(i)=K2/N1
Avol(i)=K3/N1
Aln(i)=K4/N1
! print*,Tag(i),Asl(i),Asv(i),Avol(i),Aln(i)

if(Asl(i).NE.(0.0))then
Num=Num+1
! print*,Tag(i),Asl(i),Asv(i),Avol(i),Aln(i)
! Write(3,*)Tag(i),Asl(i),Asv(i),Avol(i),Aln(i)
endif
enddo

Your help will be appreciated .

Thanks in advance

 

[xwb]

How much data is large data - more than 50?

 

[xwb]

Just a thought. Since you're reading the size, you could allocate the arrays dynamically

real,dimension(:), allocatable::Asv,k,ar3,vol,ln,Asl,Avol,Aln
...
read(1,*)N
allocate (Asv(N), k(N), ar3(N), vol(N), ln(N), Asl(N), Avol(N), Aln(N))
do i = 1,N

I don't know if ln is an intrinsic function for natural logs. Be aware of that if your program exhibits strange behaviour when you build on other platforms.

 

[swampyankee]

Neglecting the rather obvious problem -- your array is sized at 50, but you don't check to make sure N doesn't exceed that -- and walking off the end of an array in Fortran is just as easy as doing so in C, and will have equally unpredictable results.

0: When you read N make sure its value does not exceed the value of max.

1: Check the read statement's iostat result, especially for the end-of-file condition.

2: Count the number of records as they're (successfully) read.

3: Stop reading if the number of records that has been read will exceed the value of max.

4: Check to make sure that the number of records read is equal to N.

As a general piece of advice: never assume input data are totally trustworthy.

Two stylistic criticisms: don't use multiple statements on a single line, especially if they do much more than initialize something, and the series of tautological assignments (after the else statement) are superfluous, and would likely be optimized away.

 

[clergy1122]

Thanks to all that responded. Sorry that I did write back that I had seen my mistake. My actual array size is larger than 50. It had been corrected. Thanks for other corrections about my "newbie style".