investiagate efficiency of highly mathematical functions

[Kwasniok]

e.g. calculating a metric or Christoffel symbols

potential problems:

• premature optimization due choice of intermediate variables
• memory/cache inefficiency due to the usage of too many registers
• too many calls of expensive functions like exp, cos, sin, tan, sqrt ...
• inefficient order of operations
• final values not written to final location in return memory immediately

todo:

• examine assembly on multiple architectures
• benchmark these functions on multiple architectures
• optimizing memory layout for Christoffel symbols #73