I8LIB is a C library which contains a number of utility routines for "I8" or "double precision integer" arithmetic.
The computer code and data files described and made available on this web page are distributed under the GNU LGPL license.
I8LIB is available in a C version and a C++ version and a FORTRAN77 version and a FORTRAN90 version.
C4LIB, a C library which implements certain elementary functions for "C4" or single precision complex variables;
C8LIB, a C library which implements certain elementary functions for "C8" or double precision complex variables;
I4LIB, a C library which contains many utility routines, using "I4" or "single precision integer" arithmetic.
L4LIB, a C library which contains many utility routines, using one byte logical (L4) variables.
R4LIB, a C library which contains many utility routines, using "R4" or "single precision real" arithmetic.
R8LIB, a C library which contains many utility routines, using "R8" or "double precision real" arithmetic.
You can go up one level to the C source codes.