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在定量的意义上,许多问题的研究往往可以归结为研究有关变量之间的联系.变量之间存在数量上的联系的例子是相当多的,例如,作物的产量与播种量、施肥量等因子有关;林分蓄积量与林分平均胸经、平均高和密度等指标有关;作物叶片的氮、磷含量与土壤的腐殖质、全氮、全磷、速效磷含量有关.显然,弄清楚这些变量之间的数量关系是很有实际意义的.通常,我们并不满足于定性地了解变量之间是否存在数量上的联系,而是希望在确知变量间存在联系时弄清楚这种联系的具体数学形式,即通过自变量x_1、x_2…、x把因变量y_1、y_2…、y表达出来,这就是通常所说的建立数学模型.
In the quantitative sense, many problems can often be attributed to the study of the relationship between variables. There are quite a few examples of quantitative relationships between variables, for example, crop yield, sowing rate and fertilizer application , And the amount of stand volume was related to the average chest diameter, average height and density of stands, and the contents of nitrogen and phosphorus in crop leaves were related to the contents of humus, total nitrogen, total phosphorus and available phosphorus in soil. Obviously, We usually do not want to be satisfied with qualitatively knowing whether there is a quantitative relationship between the variables or not and instead want to find out the concrete link between the variables when we know there is a link between the variables Mathematical form, that is, through the arguments x_1, x_2 ..., x to the dependent variables y_1, y_2 ..., y, which is commonly referred to as the establishment of mathematical models.