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#define FLT_EVAL_METHOD /* implementation-defined */ | | (since C++11) |
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Specifies the precision in which all floating-point arithmetic operations other than assignment and cast are done.
| Value | Explanation |
| negative values except-1 | implementation-defined behavior |
| -1 | the default precision is not known |
| 0 | all operations and constants evaluate in the range and precision of the type used. Additionally,float_t anddouble_t are equivalent tofloat anddouble respectively |
| 1 | all operations and constants evaluate in the range and precision ofdouble. Additionally, bothfloat_t anddouble_t are equivalent todouble |
| 2 | all operations and constants evaluate in the range and precision oflongdouble. Additionally, bothfloat_t anddouble_t are equivalent tolongdouble |
Regardless of the value ofFLT_EVAL_METHOD, any floating-point expression may becontracted, that is, calculated as if all intermediate results have infinite range and precision (unless#pragmaSTDC FP_CONTRACT is off).
Cast and assignment strip away any extraneous range and precision: this models the action of storing a value from an extended-precision FPU register into a standard-sized memory location.
[edit]See also
