These mathematica files validate the perterbative elasticity solution for an incompressible neo-Hookean elastic layer growing equi-biaxially sandwhiched by an infinite neo-Hookean substrate and a matching superstrate discussed in Section VII of "Pattern selection when a layer buckles on a soft substrate" by Cheewaruangroj and Biggins.

sandwich_wrinkle_validate.nb is a human-readable matheamtica file, which the user should open and run from top to bottom. Instructions are in the notebook itself. 

In more detail, the notebook sandwich_wrinkle_validate.nb

1) Computes each term in the series expansion of the bulk and boundary equations,
2) Calls the other mathematica notebooks in this file as input to load the full series solutions for the bulk equations, and the associated constants, 
3) Verifies the series solutions indeed satisfy the bulk and boundary equations,  
4) Calculates the stability threshold and the Landau energy coeficients to characterize the instability.

The notebook does steps 2-4 consecutivley for stripe, square and hexagonal buckling patterns, leading to the results for the energy coefficients given in the main manuscript.
