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捕获数学函数异常

 2010-01-23 20:32:27 来源:WEB开发网   
核心提示:注意:数学函数的错误类型定义如下:_DOMAIN 变元定义域错误;_SING 变元奇异点错误;_OVERFLOW 溢出错误;_PLOSS 精度部分遗失;_TLOSS 精度丢失;_UNDERFLOW 下溢错误,结果太小,捕获数学函数异常(3),无发表示,下面是MSDN给我们提供的一个示例供大家参考:/* MATHERR.

注意:数学函数的错误类型定义如下:

_DOMAIN 变元定义域错误;

_SING 变元奇异点错误;

_OVERFLOW 溢出错误;

_PLOSS 精度部分遗失;

_TLOSS 精度丢失;

_UNDERFLOW 下溢错误,结果太小,无发表示。

下面是MSDN给我们提供的一个示例供大家参考:

/* MATHERR.C illustrates writing an error routine for math
* functions. The error function must be:
*   _matherr
*/
#include <math.h>
#include <string.h>
#include <stdio.h>
void main()
{
/* Do several math operations that cause errors. The _matherr
* routine handles _DOMAIN errors, but lets the system handle
* other errors normally.
*/
  printf( "log( -2.0 ) = %e
", log( -2.0 ) );
  printf( "log10( -5.0 ) = %e
", log10( -5.0 ) );
  printf( "log( 0.0 ) = %e
", log( 0.0 ) );
}
/* Handle several math errors caused by passing a negative argument
* to log or log10 (_DOMAIN errors). When this happens, _matherr
* returns the natural or base-10 logarithm of the absolute value
* of the argument and suppresses the usual error message.
*/
int _matherr( struct _exception *except )
{
  /* Handle _DOMAIN errors for log or log10. */
  if( except->type == _DOMAIN )
  {
    if( strcmp( except->name, "log" ) == 0 )
    {
      except->retval = log( -(except->arg1) );
      printf( "Special: using absolute value: %s: _DOMAIN "
           "error
", except->name );
      return 1;
    }
    else if( strcmp( except->name, "log10" ) == 0 )
    {
      except->retval = log10( -(except->arg1) );
      printf( "Special: using absolute value: %s: _DOMAIN "
           "error
", except->name );
      return 1;
    }
  }
  else
  {
    printf( "Normal: " );
    return 0;  /* Else use the default actions */
  }
}

输出结果

Special: using absolute value: log: _DOMAIN error

log( -2.0 ) = 6.931472e-001

Special: using absolute value: log10: _DOMAIN error

log10( -5.0 ) = 6.989700e-001

Normal: log( 0.0 ) = -1.#INF00e+000

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Tags:捕获 数学 函数

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