.BR y0 (),
.BR y1 (),
.BR yn ():
+.RS 4
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE
+.RE
.br
.BR y0f (),
.BR y0l (),
.BR y1l (),
.BR ynf (),
.BR ynl ():
+.RS 4
_SVID_SOURCE || _BSD_SOURCE || _XOPEN_SOURCE\ >=\ 600
.\" Also seems to work: -std=c99 -D_XOPEN_SOURCE
+.RE
.ad b
.SH DESCRIPTION
.PP