text: LRINT(3) BSD Programmer's Manual LRINT(3)
  llrint, llrintf, lrint, lrintf - convert to integer
  libm
  #include <math.h> long long llrint(double x); long long llrintf(float x); long lrint(double x); long lrintf(float x);
  The lrint() function returns the integer nearest to its argument x ac- cording to the current rounding mode. The llrint(), llrintf(), and lrintf() functions differ from lrint() only in their input and output types.
  The llrint, llrintf, lrint, and lrintf functions return the integer nearest to their argument x according to the current rounding mode. If the rounded result is too large to be represented as a long long or long value, respectively, the return value is undefined.
  math(3), rint(3), round(3)
  The llrint(), llrintf(), lrint(), and lrintf() functions conform to ISO/IEC 9899:1999 ("ISO C99"). MirOS BSD #10-current January.