引用矩阵的有关理论，给出了平方和分解式中二次型秩数的计算方法。

By introducing theories of matrix, this paper presents a calculation method for the rank of the quadratic form in quadratic sum resolution.

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并用方差分析法、回归分析法和Mann - Kendall秩次检验等方法，研究了开垦河径流的分配和年际变化特征。

This paper also studied the distribution and variation characteristics over years of runoff, using variance analysis, regression analysis and Mann-Kendall test.

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