feasible descent direction

基本解释

After finite iterations, the iteration point gets into the feasible set and the master direction is a feasible direction of descent.
有限次迭代后，迭代点进入可行集且主方向是一可行下降方向。
At each iteration, the method uses a linearly constrained positive semidefinite quadratic problem to generate a feasible descent direction.
在每次迭代时，这种方法都利用一种线性约束半正定二次问题来产生一个合理的下降方向；
So at every nonstationary point there exists at least one feasible descent direction, every iterate generated by the methods is feasible so long as the initial iterate is feasible .
这样在每一个非稳定点处至少存在一个可行的下降方向，在初始点是可行点的条件下，此算法产生的每一个迭代点都是可行点。