Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Highlighted
New Contributor I
49 Views

What is IMPLICIT UNDEFINED?

Jump to solution

I am reviewing some legacy Fortran code implementing a numerical algorithm and it contains the statement IMPLICIT UNDEFINED (A-H,O-Z). I have never come across such a statement before. Is it the same as IMPLICIT NONE? It should be fairly easy to comment out or replace.

0 Kudos

Accepted Solutions
Highlighted
Black Belt
49 Views

It is an old Sun Fortran extension. You can replace it by IMPLICIT NONE and move on.

View solution in original post

0 Kudos
6 Replies
Highlighted
Black Belt
50 Views

It is an old Sun Fortran extension. You can replace it by IMPLICIT NONE and move on.

View solution in original post

0 Kudos
Highlighted
Honored Contributor I
49 Views
0 Kudos
Highlighted
New Contributor II
49 Views

Take care that

IMPLICIT UNDEFINED (A-H,O-Z)

will leave I-N implicitly defined

IMPLICIT NONE

will undefine all variables.

For me, if it is legal :

IMPLICIT NONE

IMPLICIT INTEGER (I-N)

will only be equivalent to

IMPLICIT UNDEFINED (A-H,O-Z)

0 Kudos
Highlighted
Black Belt Retired Employee
49 Views

It is legal to have multiple IMPLICIT statements as long as there is only one IMPLICIT NONE.

0 Kudos
Highlighted
New Contributor I
49 Views

The two statements are not equivalent. One defines I,J,K,L,M and N as INTEGER while the other doesn't.

mecej4 wrote:

It is an old Sun Fortran extension. You can replace it by IMPLICIT NONE and move on.

0 Kudos
Highlighted
New Contributor II
49 Views

Hi

I presumed that if the IMPLICIT UNDEFINED (A-H,O-Z) statement was used in this code it was because the compiler used to compile it always define implicit types (A-H,O-Z) as real and (I-N) as integer as old compilers used to. So the aim of this statement was to keep integer variables defined.

Otherwise, the IMPLICIT NONE statement would have been used.

0 Kudos