Why do I have to run the package to make the function available?

Question

I made the following package file :

BeginPackage["thermotoolpackage`"]

LLog[x_] := If[x != 0, Log[x], 0]

H2[x_] := (-x)*LLog[x] - (1 - x)*LLog[1 - x]

InvH2BrancheDroite[x_] := 1 - InverseFunction[H2][x]
EntropyMat[M_] := Module[{eigenValues, entropy},
  eigenValues = Eigenvalues[M];
  entropy = -Sum[
     If[eigenValues[[i]] != 0, eigenValues[[i]]*Log[eigenValues[[i]]],
       0], {i, Length[eigenValues]}]
  ]
VectToDensityMat[v_] := Module[{rho},
  rho = Array[v[[#1]]*Conjugate[v[[#2]]] &, {Length[v], Length[v]}]
  ]

test[x_] := x + 1
EndPackage[]

The cell of this package is parametrised as "initialization cell".

In my code, I first load the package :

<< thermopackage`

But all functions excepted test are recognized. If I do test[2] it does not recognize it a a function (whereas LLog, H2 etc are recognized).

I actually just reopened this old package I made in the past and wanted to add functions (like the example test), and the recent functions I added to my package aren't recognized, and I don't get why.

They are only recognized if I first open the package and run it.

How to make it work ? Mathematica seems again very complicated for a very basic task.

Answer 1

I put your code in a initialization cell and saved it to my desktop as thermopkg.wl. I quit my local and restarted it fresh notebook. I load your package with

Needs["thermotoolpackage`", FileNameJoin[{$HomeDirectory, "Desktop", "thermopkg.wl"}]]

I then evaluated

?? test

and got

So it looked like test was loaded OK, and I tried

test[42]

43

I infer from this that there nothing intrinsically wrong with your pacakage and your problems problems reside from trying to load the package into a notebook that had conflicting symbols defined.

BTW, it is better to write packages in the package editor that in a notebook. You can do that by opening a new package editor window with File > New > Package.