Modifying transient_heat_equation.jl

[Avina-cK]

• Added reference to fe_intro for derivation and discretisation.
• Changed notation of trial functions to be consistent with previous tutorials (v -> δu).
• Modified doassembly functions into one function for K, M and f. (If there is a reason why they were in two different function, please let me know since I am new to this library).

[Avina-cK]

minor formatting corrections.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 94.25%. Comparing base (2ecfdd4) to head (745a28d).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1304   +/-   ##
=======================================
  Coverage   94.25%   94.25%           
=======================================
  Files          40       40           
  Lines        6757     6757           
=======================================
  Hits         6369     6369           
  Misses        388      388           

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[termi-official]

You have some trailing white spaces (https://github.com/Ferrite-FEM/Ferrite.jl/actions/runs/23051101170/job/66952242317?pr=1304). These can be automatically removed by running runic. Will try to give you a detailed review later today.

[fredrikekre]

IIRC there is an argument for not using δu for the transient problem since the test functions isn't really a variation of u, but I don't recall the details.

[Avina-cK]

IIRC there is an argument for not using δu for the transient problem since the test functions isn't really a variation of u, but I don't recall the details.

That makes sense. Perhaps we could switch to another symbol for test functions. I propose φ. The use of v can be a bit confusing because it's used as a second variable, after u.