is often used in algorithms that depend on the results of expensive computations that don't depend on the input of the algorithm. A trivial example of precomputation is the use of hardcoded mathematical constants, such as π and e, rather than computing their approximations to the necessary precision at run time. wikipedia 
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> Table Lookup (of gathered experience) […];
Graph algorithms (table to graph transformation) page
[…] a Node can perform a simple table lookup operation augmented with extrapolation or interpolation techniques to determine and apply the best 𝛼 and 𝛽 settings in response to dynamically changing conditions. The lookup time is O(1) and can be efficiently applied at runtime.