"If x is 0.0, -HUGE_VAL shall be returned" is specified for y0,y1,yn
but yn(1,x) == -yn(-1,x) so this is incorrect mathematically
http://pubs.opengroup.org/onlinepubs/9699919799/functions/yn.html
"If x is 0.0, -HUGE_VAL shall be returned" is specified for y0,y1,yn
but yn(1,x) == -yn(-1,x) so this is incorrect mathematically
http://pubs.opengroup.org/onlinepubs/9699919799/functions/yn.html