intro - introduction to library functions
This section describes functions that may be found in various libraries, other than those
functions that directly invoke UNIX system primitives, which are described in section 2.
Functions are divided into various libraries distinguished by the section number at the
top of the page:
(3) These functions, together with those of section 2 and those marked (3S), constitute
library libc, which is automatically loaded by the C compiler cc(1) and the Fortran
compiler f77(1). The link editor ld(1) searches this library under the `-lc'
option. Declarations for some of these functions may be obtained from include files
indicated on the appropriate pages.
(3M) These functions constitute the math library, libm. They are automatically loaded as
needed by the Fortran compiler f77(1). The link editor searches this library under
the `-lm' option. Declarations for these functions may be obtained from the include
(3S) These functions constitute the `standard I/O package', see stdio(3). These func-
tions are in the library libc already mentioned. Declarations for these functions
may be obtained from the include file <stdio.h>.
(3X) Various specialized libraries have not been given distinctive captions. The files
in which these libraries are found are named on the appropriate pages.
/lib/libm.a, /usr/lib/libm.a (one or the other)
stdio(3), nm(1), ld(1), cc(1), f77(1), intro(2)
Functions in the math library (3M) may return conventional values when the function is
undefined for the given arguments or when the value is not representable. In these cases
the external variable errno (see intro(2)) is set to the value EDOM or ERANGE. The values
of EDOM and ERANGE are defined in the include file <math.h>.
In assembly language these functions may be accessed by simulating the C calling sequence.
For example, ecvt(3) might be called this way: