FMOD(3P) POSIX Programmer's Manual FMOD(3P) PROLOG This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux. NAME fmod, fmodf, fmodl — floating-point remainder value function SYNOPSIS #include <math.h> double fmod(doublex, doubley); float fmodf(floatx, floaty); long double fmodl(long doublex, long doubley); DESCRIPTION The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of POSIX.1‐2008 defers to the ISO C standard. These functions shall return the floating-point remainder of the division ofxbyy. An application wishing to check for error situations should seterrnoto zero and callfeclearexcept(FE_ALL_EXCEPT) before calling these functions. On return, iferrnois non-zero orfetestexcept(FE_INVALID | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has occurred. RETURN VALUE These functions shall return the valuex−i*y, for some integerisuch that, ifyis non-zero, the result has the same sign asxand magnitude less than the magnitude ofy. If the correct value would cause underflow, and is not representable, a range error may occur, andfmod(),modf(), andfmodl() shall return 0.0, or (if the IEC 60559 Floating-Point option is not supported) an implementation-defined value no greater in magnitude than DBL_MIN, FLT_MIN, and LDBL_MIN, respectively. Ifxoryis NaN, a NaN shall be returned. Ifyis zero, a domain error shall occur, and a NaN shall be returned. Ifxis infinite, a domain error shall occur, and a NaN shall be returned. Ifxis ±0 andyis not zero, ±0 shall be returned. Ifxis not infinite andyis ±Inf,xshall be returned. If the correct value would cause underflow, and is representable, a range error may occur and the correct value shall be returned. ERRORS These functions shall fail if: Domain Error Thexargument is infinite oryis zero. If the integer expression (math_errhandling& MATH_ERRNO) is non-zero, thenerrnoshall be set to[EDOM]. If the integer expression (math_errhandling& MATH_ERREXCEPT) is non-zero, then the invalid floating-point exception shall be raised. These functions may fail if: Range Error The result underflows. If the integer expression (math_errhandling& MATH_ERRNO) is non-zero, thenerrnoshall be set to[ERANGE]. If the integer expression (math_errhandling& MATH_ERREXCEPT) is non-zero, then the underflow floating-point exception shall be raised.The following sections are informative.EXAMPLES None. APPLICATION USAGE On error, the expressions (math_errhandling& MATH_ERRNO) and (math_errhandling& MATH_ERREXCEPT) are independent of each other, but at least one of them must be non-zero. RATIONALE None. FUTURE DIRECTIONS None. SEE ALSOfeclearexcept(),fetestexcept(),isnan()Section 4.19,Treatment of Error Conditions for Mathematical Functions,<math.h>COPYRIGHT Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.unix.org/online.html . Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html . IEEE/The Open Group 2013 FMOD(3P)