fudge factor

( n.)

   [common]  A  value  or  parameter  that is varied in an ad hoc way to
   produce  the  desired result. The terms tolerance and {slop} are also
   used,  though  these  usually  indicate a one-sided leeway, such as a
   buffer  that  is  made  larger  than necessary because one isn't sure
   exactly  how large it needs to be, and it is better to waste a little
   space  than to lose completely for not having enough. A fudge factor,
   on the other hand, can often be tweaked in more than one direction. A
   good   example  is  the  fuzz  typically  allowed  in  floating-point
   calculations: two numbers being compared for equality must be allowed
   to  differ  by  a  small  amount;  if  that  amount  is  too small, a
   computation  may  never  terminate, while if it is too large, results
   will  be needlessly inaccurate. Fudge factors are frequently adjusted
   incorrectly  by  programmers who don't fully understand their import.
   See also {coefficient of X}.

[glossary]
[Reference(s) to this entry by made by: {coefficient of X}{slop}{tweak}]