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MATH_ERRNO, MATH_ERREXCEPT, math_errhandling

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math_errhandlingMATH_ERRNOMATH_ERREXCEPT
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Template:ddcl list begin <tr class="t-dsc-header">

<td>
Defined in header <cmath>
</td>

<td></td> <td></td> <tr class="t-dcl ">

<td >
#define MATH_ERRNO        1
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
#define MATH_ERREXCEPT    2
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> <tr class="t-dcl ">

<td >
#define math_errhandling  /*implementation defined*/
</td>

<td class="t-dcl-nopad"> </td> <td > (since C++11) </td> </tr> Template:ddcl list end

The macro constant math_errhandling expands to an expression of type int that is either equal to MATH_ERRNO, or equal to MATH_ERREXCEPT, or equal to their bitwise OR (MATH_ERRNO | MATH_ERREXCEPT).

The value of math_errhandling indicates the type of error handling that is performed by the floating-point operators and functions:

Constant Explanation
MATH_ERREXCEPT indicates that floating-point exceptions are used: at least FE_DIVBYZERO, FE_INVALID, and FE_OVERFLOW are defined in <cfenv>.
MATH_ERRNO indicates that floating-point operations use the variable errno to report errors.


The following floating-point error conditions are recognized:

  1. Domain error (input argument is outside the range in which the operation is mathematically defined, e.g. std::sqrt(-1), std::log(-1), or std::acos(2)). If MATH_ERRNO bit is set, EDOM is assigned to errno. If MATH_ERREXCEPT bit is set, FE_INVALID is raised.
  2. Range error (the mathematical result cannot be represented as the object of specified type, e.g. std::atanh(-1), std::log(0.0), or std::lgamma(0.0)). If MATH_ERRNO bit is set, ERANGE is assigned to errno. If MATH_ERREXCEPT bit is set, FE_DIVBYZERO or FE_OVERFLOW is raised.
  3. Overflow (the mathematical result is finite, but too big to be represented without extreme roundoff error, e.g. functions such as std::exp with sufficiently large arguments). If MATH_ERRNO bit is set, ERANGE is assigned to errno. If MATH_ERREXCEPT bit is set, FE_OVERFLOW is raised.
  4. Underflow (the mathematical result is non-zero, but too small to be represented without extreme roundoff error, e.g. the result is subnormal, as in std::sin(subnormal) or for many other functions with subnormal arguments). If MATH_ERRNO bit is set, ERANGE may be assigned to errno. If MATH_ERREXCEPT bit is set, FE_UNDERFLOW may be raised.

Example

See also

Template:cpp/numeric/fenv/dcl list FE exceptionsTemplate:cpp/error/dcl list errno