1013 B
1013 B
[linalg.helpers.imag]
29 Numerics library [numerics]
29.9 Basic linear algebra algorithms [linalg]
29.9.7 Exposition-only helpers [linalg.helpers]
29.9.7.4 imag-if-needed [linalg.helpers.imag]
The name imag-if-needed denotes an exposition-only function object.
The expression imag-if-needed(E) for a subexpression E whose type is T is expression-equivalent to:
imag(E), if T is not an arithmetic type and the expression imag(E) is valid, with overload resolution performed in a context that includes the declarationtemplate U imag(const U&) = delete; If the function selected by overload resolution does not return the imaginary part of its input, the program is ill-formed, no diagnostic required;
otherwise, ((void)E, T{}).