计量学中浮点运算造成的痕量偏差对数据修约的影响及解决方案

Influence of trace deviation caused by floating point operation on data rounding in metrology and the solution

介绍了两种实现“奇进偶不进”修约规则的典型方法,方法一是先对被修约数进行“四舍五入”运算,再使用MOD函数(求余函数)判断修约目标最后一位数字的奇偶性,然后对运算结果进行修正;方法二是先通过MOD函数对被修约最后一位数字的奇偶性进行判断,再采用IF函数选择向上修约还是向下修约。计算机程序是采用二进制的方式进行数据存储,采用浮点运算进行数据运算,这会造成计算机计算结果与实际计算结果之间的极为微小的偏差,会对上述典型方法的修约造成影响。以酸度计检定项目自动化修约为例,介绍了计算机浮点运算在修约过程中对计算结果产生的痕量影响。这种影响具有一定的不确定性并且会累积,会导致部分修约结果产生错误,通过用范围判断取代单点判断的方法来消除这种影响,从而保证修约结果的准确。

Two typical methods to realize the rounding rule of"odd number round up and even number round down"were introduced.The first method was to perform the"rounding"operation on the number,then use the MOD function to judge the parity of the last significant digit of the data,and then correct the operation result;the second method was to judge the parity of the last significant digit of the data by the MOD function,and then used the IF function to select whether to round up or down.The computer program uses binary method for data storage and floating point operation for data operation,which will cause a very small deviation between the computer calculation results and the actual calculation results,and will affect the repair of the above typical methods.Taking the automatic rounding off of acidity meter verification items as an example,the trace influence of computer floating point operation on the calculation results in the rounding off process was introduced.This kind of influence had certain uncertainty and will accumulated,which will lead to errors in some rounding off results.The method of replacing single point judgment with range judgment was used to eliminate this influence,so as to ensure the correctness of rounding off results.