Calculation for elastic stability in crystals. In the symmetric matrix C, we have Cij=Cji, therefore C12=C21, C13=C31, ..., which is why not all matrix entries are displayed below.

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Instructions for use:

1) Do not use commas to consider decimals, use dots, that is, use 1.2, not 1,2; use 0.542, not 0,542.

2) Do not use symbols like "/" to write a fraction, write the number in decimal form, that is, write 0.1, not 1/10, write 0.8, not 4/5, ...

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