seo链接优化建议,南京seo优化培训,怎么做网站代购,专业网站制作网络公司向量场中的几个恒等式
1. ∇ 2 A ∇ ∇ ⋅ A − ∇ ∇ A \nabla ^2 A \nabla \nabla\cdot A-\nabla \times\nabla\times A ∇2A∇∇⋅A−∇∇A
2. ∇ ⋅ ∇ A 0 \nabla \cdot \nabla \times A 0 ∇⋅∇A0
3. ∇ ∇ ϕ 0 \nabla \times \nabla \phi0 ∇∇ϕ0向量场中的几个恒等式
1. ∇ 2 A = ∇ ∇ ⋅ A − ∇ × ∇ × A \nabla ^2 A =\nabla \nabla\cdot A-\nabla \times\nabla\times A ∇2A=∇∇⋅A−∇×∇×A
2. ∇ ⋅ ∇ × A = 0 \nabla \cdot \nabla \times A = 0 ∇⋅∇×A=0
3. ∇ × ∇ ϕ = 0 \nabla \times \nabla \phi=0 ∇×∇ϕ=0
