Pierre ALBARÈDE
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I add an answer because I need more space. Consider for example Wolfram for Software Developers and more particularly the link Wolfram language for Jupyter. The Wolfram language being passed to ...

"I want to get a decimal representation" is not compatible with infinite precision because some rational numbers like 1/3 have infinite decimal representation that does not fit into a ...

The actual output is Function[0, 999][0]. I have guessed (I hope correctly) that the expected value was 999 as from Function[a, 999][0]. In Trace[f[999], TraceOff -> Message], the essential part ...

You play a syntax puzzle. In order to see what is going on: {Sow[1]; 2; Sow[3]; 4; 5} // (Reap1 /* Last1) (* Last1[Reap1[{5}]] *) The Last of a Reap that sows nothing is obviously the empty list. {...

When OptionsPattern[] is used, OptionValue@k2 is supposed to work too, so behind the scene there is something like k2/:OptionValue@k2=3 which fails if k2 is replaced by f1[k2]: you would get a "...

The link for Tensorial above is dead, you may find something interesting on J. F. Gouyet's page. I prefer in general not to use packages and make my own simple cooking. Also there are two functions ...

By analogy with Python for example, I suggest that the Wolfram language be everything that can be interpreted in the command line. e. g. wolfram on the Raspberry pi or mathematica on other machines. ...

An example, just to summarize the main points: test = Text[ Style[#, FontSlant -> Plain, FontSize -> 32], {0, 0}] & /@ {Indexed[P, {i, j}], P} Graphics /@ test Graphics[#, ...

You get a lot of red ink. Try to simplify. Avoid complicated notations. The most useful formula: f1[x_,y_]:=f2[x,y] where f2 must not call f1 to avoid recursion (unless you want it). Don't use ...

In[28]:= q_ -> # &@2 Out[28]= q_ -> 2

{x, y, g, a, b, c} /. {x_, y_, g_, next___} :> f1[{{x, y}, g}, f2@next] and replace f1, f2 by whatever you need.

v12.2 update. If you have just inserted the line, then Undo will remove it. If the line is at the same height as an edge of the right bracket of a cell, then select this cell, go to menu Insert > ...

The normal way is simply FD1[(d - 1)/t, η] - FD1[(d - 1)/t, η - vd]/.AsymptoticSolve[eqn, {ηs, 2^(-(t/d)) nd^(t/d)}, {vd, 0, 2}]

My program is not bad but has design flaws: the Rational option is useless and the interface will fail in certain cases. So I need to update: Attributes@bisection = {HoldAll}; bisection::...

Attributes@bisection = {HoldAll}; bisection::nochangeofsign = "sign does not change, try other bounds"; Options@bisection = {AccuracyGoal -> \$MachinePrecision/2, Rational -> False}; Clear@...

I can answer on that: Why the hell is there no straightforward way to embed entire custom stylesheets in a notebook? Don't hack this on any important document! Open the notebook where you want ...

Try f[t_] := 0 /; 0 < t < 1 see also Step and PieceWise in the documentation.

Question 1 : pressure is arbitrary for any uniform shift because the gradient of uniform function is zero. There is little relation between the downstream BC and the initial conditions on pressure. ...

[Sorry this is comment again but does not fit in the box so I put answer again.] I have had a look at the tutorial and the program. There is inconsistency in your question but maybe not in the ...

Very interesting but not clear. "initial pressure value from 𝑝(0,𝑥,𝑦)=0" so first coordinate must be time. Then "the boundary condition says 𝑝(0,𝑥,𝑦)=0,𝑥==𝑒𝑛𝑑". If the first coordinate ...

For Newton FindRoot[{x^5 - x + 1 == 0}, {x, 1}] Then check the details with Options@FindRoot Check in the documentation the option Method in particular. For the bisection method, NSolve may use ...

In general you would use Solve but here it is straightforward: C1=0.2-xp[0] and I let you write the initial equation for C2.

The Wolfram language is more an informal abstraction than an implementation of Mathematica. A formal or normative definition does not exist yet after many years but three important events have ...

I suspect that the problem is undecidable, except for particulars classes of expressions, e. g., rational expressions.

In your program you can replace "a" by a to make it more general. As Mathematica is symbolic, you don't need to quote symbols. Replacing x by OptionValue@x or even OV@x in a complex expression may ...

If you put the button in a normal cell of the same notebook, you gain nothing because you can't easily access the button, so you must put the button in a palette or dock cell. To make it simple, I ...

Let me rephrase as a recipe. Do Format > Edit style sheet. The private style sheet opens: it is a notebook titled "Private style definitions for [your notebook]". In this notebook, click on the link ...

Without ListConvolve: myListConvolve[kernel_, list_][n_] := Dot[Reverse@kernel, Take[RotateLeft[list, n - 1], Length[kernel]]] example: myListConvolve[{x, y}, {a, b, c, d, e, f}] /@ Range[5] ...