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### 3066. "report a domain error" in [sf.cmath]/1 is underspecified

Section: 28.7.6 [sf.cmath] Status: New Submitter: Casey Carter Opened: 2018-02-17 Last modified: 2018-06-19

Priority: 3

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Discussion:

28.7.6 [sf.cmath]/1 uses the phrase "report a domain error" (emphasis mine):

> If any argument value to any of the functions specified in this subclause is a NaN (Not a Number), the function shall return a NaN but it shall not report a domain error. Otherwise, the function shall report a domain error for just those argument values for which:

> - the function description's Returns: clause explicitly specifies a domain and those argument values fall outside the specified domain, or

> - the corresponding mathematical function value has a nonzero imaginary component, or

> - the corresponding mathematical function is not mathematically defined.

The behavior this phrase is attempting to convey is unclear. A quick search through the text of the standard for "domain error" finds only the `domain_error` exception type defined in 19.2.4 [domain.error]. Is the intent of "report a domain error" that the special math functions throw an exception of type `domain_error`, or is it that they behave as specified in C11 7.12.1 "Treatment of error conditions" para 2 which defines the term "domain error"?

[2018-06-18 after reflector discussion]

Priority set to 3

Proposed resolution: