positive definiteness covariance

例句：

1. 1. In statistics, positive definiteness is a crucial concept in determining the reliability of data.
   在统计学中，正定性是确定数据可靠性的关键概念。
2. 2.The study of covariance is essential for understanding how variables interact and influence each other.
   协方差的研究对于理解变量如何相互作用和相互影响至关重要。
3. 3. The researchers found that the positive definiteness of the data had a significant impact on the results.
   研究人员发现，数据的正定性对结果有显著影响。