Divergence in Einstein notation Updated +Created
First we write a vector field as:
Note how we are denoting each component of as with a raised index.
Then, the divergence can be written in Einstein notation as:
It is common to just omit the variables of the function, so we tend to just say:
or equivalently when referring just to the operator:
Gram stain Updated +Created
List of bacteria Updated +Created
Network interface controller Updated +Created
Picnic at Hanging Rock (1975) Updated +Created
Strange quark Updated +Created
Super Mario Updated +Created
Super Nintendo Entertainment System Updated +Created
Dot product Updated +Created
The definition of the "dot product" of a general space varies quite a lot with different contexts.
Most definitions tend to be bilinear forms.
We use the unqualified generally refers to the dot product of Real coordinate spaces, which is a positive definite symmetric bilinear form. Other important examples include:
The rest of this section is about the case.
The positive definite part of the definition likely comes in because we are so familiar with metric spaces, which requires a positive norm in the norm induced by an inner product.
The default Euclidean space definition, we use the matrix representation of a symmetric bilinear form as the identity matrix, e.g. in :
so that:
English idiom Updated +Created
Pathological (mathematics) Updated +Created
Snowden (film) Updated +Created
Video 1.
Aptitude test scene from the Snowden 2016 film
. Source.
Video 2.
FISA Court Order The Guardian discussion scene from the Snowden 2016 film
. Source.
Video 3.
How is this Possible? scene from the Snowden 2016 film
. Source.
Video 4.
Fresh Brains for You scene from the Snowden 2016 film
. Source.
Thermodynamics Updated +Created
Human essential fatty acid Updated +Created
Marsupial Updated +Created
They split up from the rest of the mammals after the monotremes.
Every other mammal has a placenta.
This baby in pouch thing just feels like a pre-placenta stage.
Multicellularity is polyphyletic Updated +Created
From Wikipedia:
Multicellularity has evolved independently at least 25 times in eukaryotes
and:
Complex multicellular organisms evolved only in six eukaryotic groups: animals, symbiomycotan fungi, brown algae, red algae, green algae, and land plants.

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