FORTRAN compiler warning: obsolete arithmetic IF statement

Question

I have a gfortran error:

Warning: Obsolete: arithmetic IF statement at (1) 

What does this mean? In the source (old source):

6         


        

Answer 1

Quoth Wikipedia:

"..the Fortran statement defines three different branches depending on whether the result of an expression was negative, zero, or positive, in said order..."

"..was finally labeled obsolescent in Fortran 90."