what is difference between two command "ifort -O3 -o" and "ifort -o"????

[hamid_mosaddeghi]

I have two code as write with forran, I can compile them with two command:

### ifort -O3 -o

and

### ifort -o

what is difference between two command? which of them is better used?


Hamid Mosaddeghi

[Ron_Green · Accepted solution]

-O is optimization level. 3 is the highest optimization.

In the second case, you do not use a -O option, so it defaults to -O2

You'll have to compare runtimes and results to see if they are interchangeable. In general, -O2 is sufficient but sometimes you get a faster application with -O3. It depends on the code.

ron