The POSIX/iX library consists of three relocatable library files:
The file /lib/libc.a is a relocatable library file that includes C library functions defined by ANSI C, the POSIX.1 standard, and IEEE P1003.2/D11.2.
The file /lib/libm.a is a relocatable library file containing all ANSI C math library functions.
The file /lib/libM.a is a relocatable library file containing all common usage math library functions.
The POSIX/iX library |
 |
The POSIX/iX library file, /lib/libc.a, contains four classes of C library functions:
functions defined by ANSI C
functions defined by the POSIX.1 standard
functions defined by IEEE P1003.2/D11.2
functions provided to increase portability between MPE/iX and HP-UX
The common usage math library |
 |
The common usage math library consists of the same library functions available in the POSIX/iX math library; however, common usage math library functions perform in a pre-ANSI manner that does not conform to either ANSI C or the POSIX.1 standard.
The primary difference between the two math libraries is the manner in which errors are handled, such as attempting to compute the square root of a negative value. POSIX/iX math library behavior causes the library to call a user-written function named _matherr if one is provided, and no error message is displayed. Common usage math library behavior causes the library to call a user-written function named matherr if one is provided; otherwise, an error message is displayed.