| Common mathematical functions | |||||||||||||||||||||||||||||||
| Mathematical special functions(C++17) | |||||||||||||||||||||||||||||||
| Mathematical constants(C++20) | |||||||||||||||||||||||||||||||
| Basic linear algebra algorithms(C++26) | |||||||||||||||||||||||||||||||
| Data-parallel types (SIMD)(C++26) | |||||||||||||||||||||||||||||||
| Floating-point environment(C++11) | |||||||||||||||||||||||||||||||
| Complex numbers | |||||||||||||||||||||||||||||||
Numeric array (valarray) | |||||||||||||||||||||||||||||||
| Pseudo-random number generation | |||||||||||||||||||||||||||||||
| Bit manipulation(C++20) | |||||||||||||||||||||||||||||||
| Saturation arithmetic(C++26) | |||||||||||||||||||||||||||||||
| Factor operations | |||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||
| Interpolations | |||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||
| Generic numeric operations | |||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||
| C-style checked integer arithmetic | |||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||
| Nearest integer floating point operations | |||||||||||||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||||||||||||
| Floating point manipulation functions | |||||||||||||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||||||||||||
| Classification and comparison | |||||||||||||||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||||||||||||||
| Types | |||||||||||||||||||||||||||||||||||||||||
| Macro constants | |||||||||||||||||||||||||||||||||||||||||
|
| ||||||||||||||||||||||||||||||||||||||||
Defined in header <cmath> | ||
| (1) | ||
float fmod(float x,float y); double fmod(double x,double y); | (until C++23) | |
constexpr/*floating-point-type*/ fmod(/*floating-point-type*/ x, | (since C++23) | |
float fmodf(float x,float y); | (2) | (since C++11) (constexpr since C++23) |
longdouble fmodl(longdouble x,longdouble y); | (3) | (since C++11) (constexpr since C++23) |
SIMD overload(since C++26) | ||
Defined in header <simd> | ||
template<class V0,class V1> constexpr/*math-common-simd-t*/<V0, V1> | (S) | (since C++26) |
Additional overloads(since C++11) | ||
Defined in header <cmath> | ||
template<class Integer> double fmod( Integer x, Integer y); | (A) | (constexpr since C++23) |
std::fmod for all cv-unqualified floating-point types as the type of the parameters.(since C++23)S) The SIMD overload performs an element-wise std::fmod onv_xandv_y.
| (since C++26) |
A) Additional overloads are provided for all integer types, which are treated asdouble. | (since C++11) |
The floating-point remainder of the division operationx/ y calculated by this function is exactly the valuex- iquot* y, whereiquot isx/ y with its fractional part truncated.
The returned value has the same sign asx and is less thany in magnitude.
Contents |
| x, y | - | floating-point or integer values |
If successful, returns the floating-point remainder of the divisionx/ y as defined above.
If a domain error occurs, an implementation-defined value is returned (NaN where supported).
If a range error occurs due to underflow, the correct result (after rounding) is returned.
Errors are reported as specified inmath_errhandling.
Domain error may occur ify is zero.
If the implementation supports IEEE floating-point arithmetic (IEC 60559),
POSIX requires that a domain error occurs ifx is infinite ory is zero.
std::fmod, but notstd::remainder is useful for doing silent wrapping of floating-point types to unsigned integer types:(0.0<=(y= std::fmod(std::rint(x),65536.0))? y:65536.0+ y) is in the range[-0.0, 65535.0], which corresponds tounsignedshort, butstd::remainder(std::rint(x),65536.0 is in the range[-32767.0, +32768.0], which is outside of the range ofsignedshort.
Thedouble version ofstd::fmod behaves as if implemented as follows:
double fmod(double x,double y){#pragma STDC FENV_ACCESS ONdouble result=std::remainder(std::fabs(x), y=std::fabs(y));if(std::signbit(result)) result+= y;returnstd::copysign(result, x);}
The expressionx-std::trunc(x/ y)* y may not equalstd::fmod(x, y), when the rounding ofx/ y to initialize the argument ofstd::trunc loses too much precision (example:x=30.508474576271183309,y=6.1016949152542370172).
The additional overloads are not required to be provided exactly as(A). They only need to be sufficient to ensure that for their first argumentnum1 and second argumentnum2:
| (until C++23) |
Ifnum1 andnum2 have arithmetic types, thenstd::fmod(num1, num2) has the same effect asstd::fmod(static_cast</*common-floating-point-type*/>(num1), If no such floating-point type with the greatest rank and subrank exists, thenoverload resolution does not result in a usable candidate from the overloads provided. | (since C++23) |
#include <cfenv>#include <cmath>#include <iostream>// #pragma STDC FENV_ACCESS ON int main(){std::cout<<"fmod(+5.1, +3.0) = "<< std::fmod(5.1,3)<<'\n'<<"fmod(-5.1, +3.0) = "<< std::fmod(-5.1,3)<<'\n'<<"fmod(+5.1, -3.0) = "<< std::fmod(5.1,-3)<<'\n'<<"fmod(-5.1, -3.0) = "<< std::fmod(-5.1,-3)<<'\n'; // special valuesstd::cout<<"fmod(+0.0, 1.0) = "<< std::fmod(0,1)<<'\n'<<"fmod(-0.0, 1.0) = "<< std::fmod(-0.0,1)<<'\n'<<"fmod(5.1, Inf) = "<< std::fmod(5.1,INFINITY)<<'\n'; // error handlingstd::feclearexcept(FE_ALL_EXCEPT);std::cout<<"fmod(+5.1, 0) = "<< std::fmod(5.1,0)<<'\n';if(std::fetestexcept(FE_INVALID))std::cout<<" FE_INVALID raised\n";}
Possible output:
fmod(+5.1, +3.0) = 2.1fmod(-5.1, +3.0) = -2.1fmod(+5.1, -3.0) = 2.1fmod(-5.1, -3.0) = -2.1fmod(+0.0, 1.0) = 0fmod(-0.0, 1.0) = -0fmod(5.1, Inf) = 5.1fmod(+5.1, 0) = -nan FE_INVALID raised
(C++11) | computes quotient and remainder of integer division (function)[edit] |
(C++11)(C++11)(C++11) | signed remainder of the division operation (function)[edit] |
(C++11)(C++11)(C++11) | signed remainder as well as the three last bits of the division operation (function)[edit] |
C documentation forfmod | |
