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

Check here:

http://www.ibiblio.org/pub/languages/fortran/ch1-5.html

"The Arithmetic IF is considered harmful."

Your statement,

if (s12 - 1.0) 13, 13, 12 is an Arithmetic IF, and is considered bad programming.