"在某一点的方向导数的值因方向的变化而不同",if down still brings out volume, then is likely still down, until it becomes 标量
于是矢量,开始向上
• “从向量场推导流” -marketreflections- ♂ (9454 bytes) () 12/31/2010 postreply 14:04:18
• 广义相对论继承了狭义相对论中‘光速不变’的基本假设,但把其适用范围缩小到只限于所涉及的时-空点附近的局部区域 -marketreflections- ♂ (573 bytes) () 12/31/2010 postreply 17:35:36