1FMOD(3P) POSIX Programmer's Manual FMOD(3P)
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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.
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13 fmod, fmodf, fmodl — floating-point remainder value function
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16 #include <math.h>
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18 double fmod(double x, double y);
19 float fmodf(float x, float y);
20 long double fmodl(long double x, long double y);
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23 The functionality described on this reference page is aligned with the
24 ISO C standard. Any conflict between the requirements described here
25 and the ISO C standard is unintentional. This volume of POSIX.1‐2008
26 defers to the ISO C standard.
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28 These functions shall return the floating-point remainder of the divi‐
29 sion of x by y.
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31 An application wishing to check for error situations should set errno
32 to zero and call feclearexcept(FE_ALL_EXCEPT) before calling these
33 functions. On return, if errno is non-zero or fetestexcept(FE_INVALID |
34 FE_DIVBYZERO | FE_OVERFLOW | FE_UNDERFLOW) is non-zero, an error has
35 occurred.
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38 These functions shall return the value x−i*y, for some integer i such
39 that, if y is non-zero, the result has the same sign as x and magnitude
40 less than the magnitude of y.
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42 If the correct value would cause underflow, and is not representable, a
43 range error may occur, and fmod(), modf(), and fmodl() shall return
44 0.0, or (if the IEC 60559 Floating-Point option is not supported) an
45 implementation-defined value no greater in magnitude than DBL_MIN,
46 FLT_MIN, and LDBL_MIN, respectively.
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48 If x or y is NaN, a NaN shall be returned.
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50 If y is zero, a domain error shall occur, and a NaN shall be returned.
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52 If x is infinite, a domain error shall occur, and a NaN shall be
53 returned.
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55 If x is ±0 and y is not zero, ±0 shall be returned.
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57 If x is not infinite and y is ±Inf, x shall be returned.
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59 If the correct value would cause underflow, and is representable, a
60 range error may occur and the correct value shall be returned.
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63 These functions shall fail if:
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65 Domain Error
66 The x argument is infinite or y is zero.
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68 If the integer expression (math_errhandling & MATH_ERRNO)
69 is non-zero, then errno shall be set to [EDOM]. If the
70 integer expression (math_errhandling & MATH_ERREXCEPT) is
71 non-zero, then the invalid floating-point exception shall
72 be raised.
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74 These functions may fail if:
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76 Range Error The result underflows.
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78 If the integer expression (math_errhandling & MATH_ERRNO)
79 is non-zero, then errno shall be set to [ERANGE]. If the
80 integer expression (math_errhandling & MATH_ERREXCEPT) is
81 non-zero, then the underflow floating-point exception shall
82 be raised.
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84 The following sections are informative.
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87 None.
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90 On error, the expressions (math_errhandling & MATH_ERRNO) and
91 (math_errhandling & MATH_ERREXCEPT) are independent of each other, but
92 at least one of them must be non-zero.
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95 None.
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98 None.
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101 feclearexcept(), fetestexcept(), isnan()
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103 Section 4.19, Treatment of Error Conditions for Mathematical Functions,
104 <math.h>
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107 Portions of this text are reprinted and reproduced in electronic form
108 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
109 -- Portable Operating System Interface (POSIX), The Open Group Base
110 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
111 cal and Electronics Engineers, Inc and The Open Group. (This is
112 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
113 event of any discrepancy between this version and the original IEEE and
114 The Open Group Standard, the original IEEE and The Open Group Standard
115 is the referee document. The original Standard can be obtained online
116 at http://www.unix.org/online.html .
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118 Any typographical or formatting errors that appear in this page are
119 most likely to have been introduced during the conversion of the source
120 files to man page format. To report such errors, see https://www.ker‐
121 nel.org/doc/man-pages/reporting_bugs.html .
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125IEEE/The Open Group 2013 FMOD(3P)