What is the difference between f77 and Intel Visual Fortran Compilers in terms of computation

[mayank8281]

Hi,

I am trying to compile and run a f77 fortran code through Intel Visual Fortran compiler. However, I am getting different results from the same input file from Intel Fortran compiler as compared to f77 compiler. Altough the relative error is small ,but What is the cause of this error?

I have read an article that f77 is a fixed form while the higher versions are free form and compiling a fixed form source code with free form compiler may give compilation errors. What is the difference between fixed form and free form? If there is compilation error, then how to fix it?

[mayank8281]

Hi Tim,
Thanks for your reply.

I have declared 'implicit none' in my fortran code. However , there are many variables which are not declared explicitly of any data type( nor as common variable) in the subroutines. when I compile the code it shows no error even though I have defined implicit none!. Is the compiler still treating these variables with implicit data types?

Any suggestions would be helpful.

[TimP]

implicit none takes effect only in the subroutine where it is present. If you didn't copy it into those other subroutines, implicit typing of undeclared varables would still be in effect.