- #1
singularme
- 1
- 0
Dear all,
I encounter the following formula (for stain energy function) a lot in physics literature:
[itex]
W(\epsilon_{kl}) = \int_0^{\epsilon_{kl}} \sigma_{ij} \textrm{d}\epsilon_{ij}
[/itex]
where all indices ranges from 1 to 3, both [itex]\epsilon[/itex] and [itex]\sigma[/itex] are 3x3 matrices.
My question is what exactly does it mean in non-Einstein notation? Is it an abuse of notation? Because when I see [itex]W(\epsilon_{kl})=\cdots[/itex], I feel it should interpreted as 9 separate equations (with [itex]kl[/itex] replaced by 11, 12, 13, 21, 22, 23, 31, 32, 33), which does not make sense in this case.
Thanks a lot!
James
I encounter the following formula (for stain energy function) a lot in physics literature:
[itex]
W(\epsilon_{kl}) = \int_0^{\epsilon_{kl}} \sigma_{ij} \textrm{d}\epsilon_{ij}
[/itex]
where all indices ranges from 1 to 3, both [itex]\epsilon[/itex] and [itex]\sigma[/itex] are 3x3 matrices.
My question is what exactly does it mean in non-Einstein notation? Is it an abuse of notation? Because when I see [itex]W(\epsilon_{kl})=\cdots[/itex], I feel it should interpreted as 9 separate equations (with [itex]kl[/itex] replaced by 11, 12, 13, 21, 22, 23, 31, 32, 33), which does not make sense in this case.
Thanks a lot!
James