28 Numerics library [numerics]

28.9 Basic linear algebra algorithms [linalg]

28.9.7 Exposition-only helpers [linalg.helpers] conj-if-needed [linalg.helpers.conj]

The name conj-if-needed denotes an exposition-only function object.
The expression conj-if-needed(E) for a subexpression E whose type is T is expression-equivalent to:
  • conj(E), if T is not an arithmetic type and the expression conj(E) is valid, with overload resolution performed in a context that includes the declaration template<class T> T conj(const T&) = delete;
    If the function selected by overload resolution does not return the complex conjugate of its input, the program is ill-formed, no diagnostic required;
  • otherwise, E.