- #1
Dr. Gonzo
- 8
- 0
Hello all. Happy to have finally found this forum, sorry that it took so long!
I'm working through a Vector Algebra tutorial and I am having much difficulty with the concepts of Kronecker deltas and the Levi-Civita symbol. I can't fully grasp either of them intiutively.
From what I've been able to gather, [tex] \delta_{ij}= \left\{\begin{array}{cc}1,&\mbox{ if }i=j,\\0, & \mbox{ if } i\neq k\end{array}\right.[/tex]
I'm pretty sure this means that, in the case of two vectors I and J with components [tex] i_{1},i_{2},i_{3}[/tex] and [tex] j_{1},j_{2},j_{3} [/tex] that [tex] i_{1}= j_{1},i_{2}= j_{2}, i_{3}= j_{3} [/tex]. In other words, vectors I and J are parallel and equal. Is this correct? Or am I missing something here?
And regarding the Levi-Civita symbol, it's been pointed out to me that another name for this is the anti-symmetric tensor. Unfortunately, this hint has not helped my understanding one iota. So far, my understanding of this symbol states that it takes Kronecker's delta one step further into a third dimension or plane.
I understand that [tex] \epsilon_{ijk}=\left\{\begin{array}{cc}1,&\mbox{ if }ijk=123, 231, or 312\\-1, & \mbox{ if } ijk= 321, 213, or 132\\0, & \mbox{ if } ijk=anything else\end{array}\right.[/tex]
I am completely confused by these 123 values. What do they represent? Perhaps understanding that will help me complete this puzzle.
I appreciate all and any help on this!
I'm working through a Vector Algebra tutorial and I am having much difficulty with the concepts of Kronecker deltas and the Levi-Civita symbol. I can't fully grasp either of them intiutively.
From what I've been able to gather, [tex] \delta_{ij}= \left\{\begin{array}{cc}1,&\mbox{ if }i=j,\\0, & \mbox{ if } i\neq k\end{array}\right.[/tex]
I'm pretty sure this means that, in the case of two vectors I and J with components [tex] i_{1},i_{2},i_{3}[/tex] and [tex] j_{1},j_{2},j_{3} [/tex] that [tex] i_{1}= j_{1},i_{2}= j_{2}, i_{3}= j_{3} [/tex]. In other words, vectors I and J are parallel and equal. Is this correct? Or am I missing something here?
And regarding the Levi-Civita symbol, it's been pointed out to me that another name for this is the anti-symmetric tensor. Unfortunately, this hint has not helped my understanding one iota. So far, my understanding of this symbol states that it takes Kronecker's delta one step further into a third dimension or plane.
I understand that [tex] \epsilon_{ijk}=\left\{\begin{array}{cc}1,&\mbox{ if }ijk=123, 231, or 312\\-1, & \mbox{ if } ijk= 321, 213, or 132\\0, & \mbox{ if } ijk=anything else\end{array}\right.[/tex]
I am completely confused by these 123 values. What do they represent? Perhaps understanding that will help me complete this puzzle.
I appreciate all and any help on this!
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