compute these into Matlab  and find out why and what are they doing(in your own words)

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. Run the following commands, what do they do? triu (E) tril (E) b. What do the following do, try different numbers? triu (E, 1) tril (E, -1) c. From the lower triangular, upper triangular and diagonal you should be able to reconstruct the matrix triu (E, 1) + tril (E, -1) + diag (E) Does this reconstruct E? If not, what do you need to do to fix this?