CVF compiler setting for maximizing numerical fidelity

[TommyCee]

I now have IVF but part of the task I have involves use of CVF.  One of my big challenges is matching numerical outut via CVF (v6.6C) w/ that from IVF (v.12.1.5).  Let's focus on CVF.

I have been told that CVF settings to maximize fidelity (minimize chances for numerical differences) include the following:

     /tune:host

     /fltconsistency

     /fpe[:0-3]           (default is /fpe:3)

     /fpconstant

     /nooptimize          (choices are /optimize[:0-5])

     /notransform_loops

     /noinline

     /assume:accuracy_sensitive

Within the CVF IDE, I have been able to find all of them except /assume:accuracy_sensitive

Does anyone know where this switch might be in the CVF IDE?

[Steven_L_Intel1]

According to the CVF documentation this is under Optimizations > Allow Reordering of Floating Point Operations. Note that not all compiler options have IDE equivalents - you can always specify options under Command Line.

[TommyCee]

You were right Steve.  Though the name next to the check box bears no resemblance to the switch name added to the command line.

I just tested this switch and I must disagree with the advice that it aids numerical precision.  Au contaire.

In fact, the CVF dropdown note for this switch says:
The numeric results can be slightly different because of the way intermediate results are rounded when this option is not selected.


So, don't use /assume:accuracy_sensitive is you're interested in numerical fidelity.  For numerical fidelity, the best overall command line is probably:

/assume:minus0 /browser:"Debug/" /check:bounds /compile_only /dbglibs /debug:full /fltconsistency /fpconstant /fpe:0 /nologo /traceback /tune:host /warn:argument_checking /warn:nofileopt /warn:unused /module:"Debug/" /object:"Debug/" /pdbfile:"Debug/DF60.PDB"

[Steven_L_Intel1]

I think you misunderstand the description.  /assume:accuracy_sensitive disables optimizations that are not value-safe, such as reassociation.  Your list of options has a lot that have no effect on "numerical fidelity" and are taken from a debug configuration.