The method of judgment in quadratic form of the extreme value of multivariable function 多元函数极值和条件极值的一般判定方法
Discussion on the conditional extremum of three variable function through unconditional extremum 用无条件极值判定多元函数条件极值
Wenxue li put forward a sufficient condition of conditional extreme value with lagrange function , but his proof is wrong 摘要李文学用拉格朗日函数提出求条件极值的充分条件，但他的证明却是错误的。
This text derives out the sufficient condition again no using lagrange function , but direct eliminating a variable from the side condition to transform conditional extreme value into the unconditional extreme value 本文不用拉格朗日函数，而是直接通过消去一个变量将条件极值转化成无条件极值，重新推导出充分性条件。
The best optimum mathematical model is constituted . scalar factor of structural parameter on loop rectangular negative pressure and adsorption slide is calculated . structural parameter , air gas source pressure carrying capacity and thickness of air cell are made sure by hydrodynamics and the theory of gas lubrication 详细论述了导轨副的设计过程，运用数学上的拉格朗日条件极值求解法，建立最优化数学模型，求出环矩形负压吸附导轨的结构参数的比例情况，并运用流体力学和气体润滑理论确定了环矩形负压吸附导轨的结构参数、气源气压、承载能力和气膜厚度的确定性结论。
The theory of minimum entropy production or minimum rate of energy dissipation shows that a river is stable when it is in a relative equilibrium condition . ( 3 ) the river facies formulas of alluvial river have been developed using the theory of minimum rate of energy dissipation together with flow continuity and motion equations , suspended load transport or bed load transport equation . ( 4 ) the causes of the river patterns are explained using the theory of minimum rate of energy dissipation （ 3 ）基于最小能耗率原理，以水流能耗率作为目标函数，以水流连续方程、水流运动方程及悬移质挟沙力公式或推移质输沙率公式作为约束条件，通过对目标函数求条件极值，分别推导出以悬移质造床为主的显式河相关系式和以推移质造床为主的显式河相关系式。
