1FMOD(3P)                   POSIX Programmer's Manual                  FMOD(3P)
2
3
4

PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
10

NAME

12       fmod, fmodf, fmodl - floating-point remainder value function
13

SYNOPSIS

15       #include <math.h>
16
17       double fmod(double x, double y);
18       float fmodf(float x, float y);
19       long double fmodl(long double x, long double y);
20
21

DESCRIPTION

23       These functions shall return the floating-point remainder of the  divi‐
24       sion of x by y.
25
26       An  application  wishing to check for error situations should set errno
27       to zero and  call  feclearexcept(FE_ALL_EXCEPT)  before  calling  these
28       functions.   On return, if errno is non-zero or fetestexcept(FE_INVALID
29       | FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error  has
30       occurred.
31

RETURN VALUE

33       These functions shall return the value x- i* y, for some integer i such
34       that, if y is non-zero, the result has the same sign as x and magnitude
35       less than the magnitude of y.
36
37       If the correct value would cause underflow, and is not representable, a
38       range error may occur, and  either 0.0 (if supported), or an  implemen‐
39       tation-defined value shall be returned.
40
41       If x or y is NaN, a NaN shall be returned.
42
43       If  y  is  zero,  a domain error shall occur, and either a NaN (if sup‐
44       ported), or an implementation-defined value shall be returned.
45
46       If x is infinite, a domain error shall occur, and either a NaN (if sup‐
47       ported), or an implementation-defined value shall be returned.
48
49       If x is ±0 and y is not zero, ±0 shall be returned.
50
51       If x is not infinite and y is ±Inf, x shall be returned.
52
53       If  the  correct  value  would cause underflow, and is representable, a
54       range error may occur and the correct value shall be returned.
55

ERRORS

57       These functions shall fail if:
58
59       Domain Error
60              The x argument is infinite or y is zero.
61
62       If the integer expression (math_errhandling & MATH_ERRNO) is  non-zero,
63       then   errno  shall  be  set  to  [EDOM].  If  the  integer  expression
64       (math_errhandling &  MATH_ERREXCEPT)  is  non-zero,  then  the  invalid
65       floating-point exception shall be raised.
66
67
68       These functions may fail if:
69
70       Range Error
71              The result underflows.
72
73       If  the integer expression (math_errhandling & MATH_ERRNO) is non-zero,
74       then errno  shall  be  set  to  [ERANGE].  If  the  integer  expression
75       (math_errhandling  &  MATH_ERREXCEPT)  is  non-zero, then the underflow
76       floating-point exception shall be raised.
77
78
79       The following sections are informative.
80

EXAMPLES

82       None.
83

APPLICATION USAGE

85       On  error,  the  expressions  (math_errhandling   &   MATH_ERRNO)   and
86       (math_errhandling  & MATH_ERREXCEPT) are independent of each other, but
87       at least one of them must be non-zero.
88

RATIONALE

90       None.
91

FUTURE DIRECTIONS

93       None.
94

SEE ALSO

96       feclearexcept(), fetestexcept(), isnan(), the Base  Definitions  volume
97       of  IEEE Std 1003.1-2001,  Section  4.18, Treatment of Error Conditions
98       for Mathematical Functions, <math.h>
99
101       Portions of this text are reprinted and reproduced in  electronic  form
102       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
103       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
104       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
105       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
106       event of any discrepancy between this version and the original IEEE and
107       The Open Group Standard, the original IEEE and The Open Group  Standard
108       is  the  referee document. The original Standard can be obtained online
109       at http://www.opengroup.org/unix/online.html .
110
111
112
113IEEE/The Open Group                  2003                             FMOD(3P)
Impressum