变量

• A single index may reflect a composite, or group, of changing variables .
  指数可以用于反映一组变量的综合变化。
• An exponential function is one in which the variable appears in an exponent .
  指数函数是指数中出现变量的函数。
• A variable is a quantity to which an unlimited number of values can be assigned .
  变量是一个可以有无限数值的量。
• Accordingly the variables x and x are known as the system state variables .
  相应地,变量X和X就称之为系统的状态变量。
• The minimum number of state variables required is the order of the system .
  所需要的状态变量的最低数量是系统的阶次。
• The first invariant of strain is independent of the coordinate system being used .
  第一应变不变量与所用的坐标系无关。
• A value index measures general changes in the total value of some variable .
  价值指数用以度量某些变量的价值总量变化。
• If we drop one variable, we must also drop one equation of motion .
  如果我们去掉一个变量，则必须同时去掉一个运动方程。
• We make this distinction because continuous variables are rounded .
  我们之所以作出这样的区别是因为连续变量是四舍五入的。
• The internal energy is related to other variables through the equations of state .
  借助状态方程，内能和其它变量发生关系。