fmod, fmodf, fmodl - floating-point remainder function

       For an explanation of the terms used in this section, see attributes(7).
       ┌─────────────────────────────────────────────────────────────────────────────┬───────────────┬─────────┐
       │ Interface                                                                   │ Attribute     │ Value   │
       ├─────────────────────────────────────────────────────────────────────────────┼───────────────┼─────────┤
       │ fmod(), fmodf(), fmodl()                                                    │ Thread safety │ MT-Safe │
       └─────────────────────────────────────────────────────────────────────────────┴───────────────┴─────────┘

       Before glibc 2.10, the glibc implementation did not set errno to EDOM when a domain error occurred for an
       infinite x.

       These  functions compute the floating-point remainder of dividing x by y.  The return value is x - n * y,
       where n is the quotient of x / y, rounded toward zero to an integer.

       To obtain the modulus, more specifically, the Least Positive Residue, you will need to adjust the  result
       from fmod like so:

           z = fmod(x, y);
           if (z < 0)
                z += y;

       An alternate way to express this is with fmod(fmod(x,y)+y,y), but the second fmod() usually costs way
       more than the one branch.

       See math_error(7) for information on how to determine whether an error has occurred  when  calling  these
       functions.

       The following errors can occur:

       Domain error: x is an infinity
              errno is set to EDOM (but see BUGS).  An invalid floating-point exception (FE_INVALID) is raised.

       Domain error: y is zero
              errno is set to EDOM.  An invalid floating-point exception (FE_INVALID) is raised.

       The call fmod(372,360) returns 348.

       The call fmod(-372,360) returns -12.

       The call fmod(-372,-360) also returns -12.

       C99, POSIX.1-2001.

       The variant returning double also conforms to SVr4, 4.3BSD, C89.

       Math library (libm, -lm)

       fmod, fmodf, fmodl - floating-point remainder function

       On  success,  these  functions return the value x - n*y, for some integer n, such that the returned value
       has the same sign as x and a magnitude less than the magnitude of y.

       If x or y is a NaN, a NaN is returned.

       If x is an infinity, a domain error occurs, and a NaN is returned.

       If y is zero, a domain error occurs, and a NaN is returned.

       If x is +0 (-0), and y is not zero, +0 (-0) is returned.

remainder(3)

Linux man-pages 6.9.1                              2024-05-02                                            fmod(3)

       C11, POSIX.1-2008.

#include<math.h>doublefmod(doublex,doubley);floatfmodf(floatx,floaty);longdoublefmodl(longdoublex,longdoubley);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       fmodf(), fmodl():
           _ISOC99_SOURCE || _POSIX_C_SOURCE >= 200112L
               || /* Since glibc 2.19: */ _DEFAULT_SOURCE
               || /* glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE