My colleagues and I are looking into the accuracy of complex mathematical operations/functions with different compilers/libraries. The first version of our paper is available at: https://inria.hal.science/hal-04714173 In the Numerics [complex.transcendentals] section of the C++ standard, some functions (e.g., acos) have a remark, "Behaves the same as the C function cacos. See also: ISO/IEC 9899:2018." Others (e.g., log) have a note, "The semantics of this function are intended to be the same in C++ as they are for clog in C." Others (e.g., cos) have neither. Are these differences intentional and meaningful? I would appreciate any pointers or help in learning more. Regards, Paul