The Intel Fortran Compiler has many options that are shared with the Intel C++ Compiler. One of these is /fp (Windows) or -fp-model (Linux and Mac OS). In Intel C++, two of the values for this option, "precise" and "source", have different meanings. For C++, "precise" instructs the compiler to perform only those floating-point optimizations that are "value-safe"; that is, the optimization does not change the resulting value.
The "source" value, in addition to performing only value-safe optimizations, prevents the compiler from evaluating expressions in a higher precision than the language specifies for the operation. For example, the compiler may decide that it is faster to do a multiplication in double-precision even though the arguments are single-precision. (This often happens when SSE instructions are not being used.)
The Intel Fortran Compiler treats both "precise" and "source" the same as the C++ "source". If you specify "precise", the compiler issues this warning to alert you to this fact. If you wish to avoid the warning, specify "source" rather than "precise".
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