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      std::fdim,std::fdimf,std::fdiml

      From cppreference.com
      <cpp‎ |numeric‎ |math
       
       
       
      Common mathematical functions
      Nearest integer floating point operations
      (C++11)(C++11)(C++11)
      (C++11)
      (C++11)
      (C++11)(C++11)(C++11)
      Floating point manipulation functions
      (C++11)(C++11)
      (C++11)
      (C++11)
      Classification and comparison
      (C++11)
      (C++11)
      (C++11)
      (C++11)
      (C++11)
      (C++11)
      Types
      (C++11)
      (C++11)
      (C++11)
      Macro constants
       
      Defined in header<cmath>
      (1)
      float       fdim(float x,float y);

      double      fdim(double x,double y);

      longdouble fdim(longdouble x,longdouble y);
      		(until C++23)
      constexpr/*floating-point-type*/

                  fdim(/*floating-point-type*/ x,

                         /*floating-point-type*/ y);
      		(since C++23)
      float       fdimf(float x,float y);
      		 (2)(since C++11)
      (constexpr since C++23)
      longdouble fdiml(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>

                  fdim(const V0& v_x,const V1& v_y);
      		 (S)(since C++26)
      Defined in header<cmath>
      template<class Integer>
      double      fdim( Integer x, Integer y);
      		 (A)(constexpr since C++23)
      1-3) Returns the positive difference betweenx andy, that is, ifx> y, returnsx- y, otherwise (i.e. ifx<= y) returns+0. The library provides overloads ofstd::fdim for all cv-unqualified floating-point types as the type of the parameters.(since C++23)
      S) The SIMD overload performs an element-wisestd::fdim onv_xandv_y.
      (Seemath-common-simd-t for its definition.)
      		(since C++26)
      A) Additional overloads are provided for all integer types, which are treated asdouble.
      		(since C++11)

      Contents

      [edit]Parameters

      x, y - floating-point or integer values

      [edit]Return value

      If successful, returns the positive difference betweenx andy.

      If a range error due to overflow occurs,+HUGE_VAL,+HUGE_VALF, or+HUGE_VALL is returned.

      If a range error due to underflow occurs, the correct value (after rounding) is returned.

      [edit]Error handling

      Errors are reported as specified inmath_errhandling.

      If the implementation supports IEEE floating-point arithmetic (IEC 60559),

      • If either argument is NaN, NaN is returned.

      [edit]Notes

      Equivalent tostd::fmax(x- y,0), except for the NaN handling requirements.

      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:

      • Ifnum1 ornum2 has typelongdouble, thenstd::fdim(num1, num2) has the same effect asstd::fdim(static_cast<longdouble>(num1),
                 static_cast<longdouble>(num2))        .
      • Otherwise, ifnum1 and/ornum2 has typedouble or an integer type, thenstd::fdim(num1, num2) has the same effect asstd::fdim(static_cast<double>(num1),
                 static_cast<double>(num2))        .
      • Otherwise, ifnum1 ornum2 has typefloat, thenstd::fdim(num1, num2) has the same effect asstd::fdim(static_cast<float>(num1),
                 static_cast<float>(num2))        .
      		(until C++23)

      Ifnum1 andnum2 have arithmetic types, thenstd::fdim(num1, num2) has the same effect asstd::fdim(static_cast</*common-floating-point-type*/>(num1),
               static_cast</*common-floating-point-type*/>(num2))      , where/*common-floating-point-type*/ is the floating-point type with the greatestfloating-point conversion rank and greatestfloating-point conversion subrank between the types ofnum1 andnum2, arguments of integer type are considered to have the same floating-point conversion rank asdouble.

      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)

      [edit]Example

      Run this code
      #include <cerrno>#include <cfenv>#include <cmath>#include <cstring>#include <iostream> #ifndef __GNUC__#pragma STDC FENV_ACCESS ON#endif int main(){std::cout<<"fdim(4, 1) = "<< std::fdim(4,1)<<'\n'<<"fdim(1, 4) = "<< std::fdim(1,4)<<'\n'<<"fdim(4,-1) = "<< std::fdim(4,-1)<<'\n'<<"fdim(1,-4) = "<< std::fdim(1,-4)<<'\n'; // error handlingerrno=0;std::feclearexcept(FE_ALL_EXCEPT); std::cout<<"fdim(1e308, -1e308) = "<< std::fdim(1e308,-1e308)<<'\n'; if(errno==ERANGE)std::cout<<"    errno == ERANGE: "<<std::strerror(errno)<<'\n';if(std::fetestexcept(FE_OVERFLOW))std::cout<<"    FE_OVERFLOW raised\n";}

      Output:

      fdim(4, 1) = 3fdim(1, 4) = 0fdim(4,-1) = 5fdim(1,-4) = 5fdim(1e308, -1e308) = inf    errno == ERANGE: Numerical result out of range    FE_OVERFLOW raised

      [edit]See also

      computes absolute value of an integral value (\(\small{|x|}\)|x|)
      (function)[edit]
      (C++11)(C++11)(C++11)
      		 larger of two floating-point values
      (function)[edit]
      Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/numeric/math/fdim&oldid=160735"
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