I know there is heaps of people’s code around the forum with code that shows step by step solutions for integration. But they don’t specify where certain things happen like substitution (u sub) or recognition by integration and stuff like that. Is there a code (has to work offline) that can show you what is being made (like u sub, simplify, expand, double angle…) for each step?

# Tag: Wolfram

## Wolfram Workbench Installation Issue

In attempting to reinstall Wolfram Workbench 2.0 after a unused hiatus and system reconfiguration, I downloaded both Eclipse and Workbench. Both seem to run. However, in following the Wolfram video on installing WWB Adam Berry suggests that before getting started one should Select the Help Menu and the Install Workbench Extras. Following the video I check the box for the single available feature Subclipse to add client support for SVN source control to the WWB. In pressing Finish I get the error:

“Could not connect to update site: http://subclipse.tigris.org/update_1.6.x”

Consequently, I can not perform subsequent steps as given in the Workbench Installation Video. It seems that the subclipse.tigris.org pages references are now missing and the site is decommissioning. Checking this subclipse.tigris.org website indicates it will be gone by July 2020,but you had to ask before 1 June 2020. The files referred to no longer seem to exist. For example, there is no “Team” support as suggested in the video.

How can one resolve this issue? Is it even necessary any longer to do this? If so, how can one now setup WWB to establish the setup features referred to in the video? If not necessary, perhaps the Installation Video needs to updated.

## Wolfram Desktop 12 hangs on welcome screen (Windows)

I am unable to get past this launch logo in Wolfram Desktop on Windows:

I tried reinstalling and does’t seem to fix the problem.

## Wolfram code gives protected error

So I’m making a sort of graph with 2 main points and I’ve inspired myself on the internet and this is the final piece of code. Unfortunately it gives me a “Protected” error on multiple occasions. How do I solve this?

`In[93]:= (*Ecuațiile,ecuațiile inițiale,conectorii și parametrii modelului.*) noOfAnimals = "aniFlow.noOfAnimals"; rate = "aniFlow.rate"; equation = {populationSize'[t] == rate[t], populationSize[t] == noOfAnimals[t]}; initialEquation = {If[steadyState, populationSize'[0] == 0, populationSize[0] == initialPopulationSize]}; connectors = {aniFlow \[Element] "PredatorPrey.Components.AnimalConnector", steadyState \[Element] Booleans}; parameters = {"initialPopulationSize" -> 10, "steadyState" -> False}; mmodel = CreateSystemModel["Hare", Join[equations, initialEquations], t, connectors, <|"ParameterValues" -> parameters|>] SystemModel[mmodel, "ModelicaDisplay"] Out[99]= CreateSystemModel["Hare", Join[equations, initialEquations], t, {aniFlow \[Element] "PredatorPrey.Components.AnimalConnector", steadyState \[Element] Booleans}, <|"ParameterValues" -> {"initialPopulationSize" -> 10, "steadyState" -> False}|>] Out[100]= SystemModel[ CreateSystemModel["Hare", Join[equations, initialEquations], t, {aniFlow \[Element] "PredatorPrey.Components.AnimalConnector", steadyState \[Element] Booleans}, <|"ParameterValues" -> {"initialPopulationSize" -> 10, "steadyState" -> False}|>], "ModelicaDisplay"] (*Ieșirea reprezintă versiunea de vizualizare text Modelica a modelului \ creat*) In[116]:= model Hare parameter Real initialPopulationSize = 10; parameter Boolean steadyState = false; Real populationSize; PredatorPrey.Components.AnimalConnector aniFlow; initial equation if steadyState then der (populationSize) = 0; else populationSize = initialPopulationSize; end if; equation der (populationSize) = anyFlow.rate; populationSize = aniFlow.noOfAnimals; end Hare; Out[116]= Hare CreateSystemModel["Hare", Join[equations, initialEquations], t, {aniFlow \[Element] "PredatorPrey.Components.AnimalConnector", SteadyState \[Element] Booleans}, <|"ParameterValues" -> {"initialPopulationSize" -> 10, "steadyState" -> False}|>] During evaluation of In[116]:= Set::write: Tag Times in initialPopulationSize parameter Real is Protected. During evaluation of In[116]:= Set::write: Tag Times in Boolean parameter steadyState is Protected. Out[121]= {initial (Derivative[1][(aniFlow."aniFlow.noOfAnimals")][t] == "aniFlow.rate"[t]), initial ((aniFlow."aniFlow.noOfAnimals")[t] == "aniFlow.noOfAnimals"[t])} Out[122]= if steadyState then During evaluation of In[116]:= Set::write: Tag Times in der aniFlow.aniFlow.noOfAnimals is Protected. Out[124]= else Out[127]= {Derivative[1][(aniFlow."aniFlow.noOfAnimals")][t] == "aniFlow.rate"[t], (aniFlow."aniFlow.noOfAnimals")[t] == "aniFlow.noOfAnimals"[t]} During evaluation of In[116]:= Set::write: Tag Times in der initialPopulationSize is Protected. `

This code insert includes the errors as well.

PS: Please fix the code insert as it is garbage at the moment.

## How to reproduce Wolfram Language’s base64 encoded string with command-line tool?

With Wolfram Language:

`In[7]:= ExportString["foobar中文", "Base64"] Out[7]= "Zm9vYmFyXDo0ZTJkXDo2NTg3" `

With the closest command-line software I could think of

`echo -n 'foobar中文' | openssl base64 Zm9vYmFy5Lit5paH `

Why the difference? What’s the best way to reproduce Mathematica’s behavior?

## ImageContents not working on Wolfram Cloud iOS app

I tried using the experimental `ImageContents[]`

function, introduced in MMA 12, on my PC (using Mathematica) as well as on my iPad (using Wolfram Cloud app). On my PC it worked, but not on Wolfram Cloud. It said that it had to download some 200 MB of data from their servers, just like it did on Mathematica. However after the download nothing happened.

This was the image: https://i.stack.imgur.com/6Fd4n.jpg

And this is the result on my PC:

Does anyone know what is the issue?

## Shannon-Fano coding in Wolfram

I’m trying to make a function that codes a string of text using the Shannon-Fano method. I get characters using the `CharacterCounts`

function, and I want to make a Grid with individual characters in the first line, and the probability of them in the second line.

How do I separate the characters and their counts from the `CharacterCounts`

function output? Is it even possible?

## Wolfram Cloud Slowdown

Has anyone noticed a slowdown on Wolfram Cloud rendering? With @JanPöschko’s help I’ve been using Wolfram Cloud to share docs for my EcoEvo package. I just updated them and noticed that it takes a long time to render now.

The main Guide page takes 1 second to load, but 1 minute 40 second to make all the links active (watch the tiny blue progress bar under the “Wolfram Notebook” header). Before the page has rendered, clicking on a link brings a popup saying “Starting interactivity…” After it is done, clicking on a link is unresponsive for 25 seconds before going to the linked page.

I don’t remember it being so slow before. Has something changed?

## How can I convert this wolfram language into C language?

**Here is my code for this in Mathematica.**

f[x_] := x^2 + 4 x + 4; Solve[f[x] == 9, x]

I tried to convert it but failed.

*Here is the code for conversion*

CForm[f[x_] := x^2 + 4 x + 4]

and this

CForm[f[x_] := x^2 + 4 x + 4; Solve[f[x] == 9, x]]

The former one just outputs `Null`

, the latter one just converts the final result in the below

`List(List(Rule(x,-5)), List(Rule(x,1))) `

## How to execute an existing notebook with Wolfram Engine?

[My related question: mwe-for-compiling-functions-into-standalone-dll-and-calling-them-in-python – here I am exploring an alternative]

I have downloaded, installed and activated the wolfram engine (12.0) on Windows, and I have installed the WolframClient in my Python environment.

In python I execute

`from wolframclient.language import wl from wolframclient.evaluation import WolframLanguageSession kernelLoc = 'C:\Program Files\Wolfram Research\Wolfram Engine\12.0\WolframKernel.exe' session = WolframLanguageSession(kernelLoc) session.evaluate(wl.StringReverse('abc')) `

and the result is ‘cba’ proving that the integration is working.

I have a workbook that contains all my (valid) compilable functions.

Question: how do I load & evaluate that notebook and call the compiled functions? (I could use a package file instead if that would help)

I have not (yet) found the answer by reference to the Wolfram Client documentation

Side issue: I recall that setting up my MMA 11.0.1.0 to work with Visual Studio 2017 for C compilation was… tricky. Does the Wolfram Engine have independent setup and if so how do I apply the working config for compilation from MMA to WE? Of course, if I can load the required notebook and it just works then this becomes redundant, but… expect the not-to-be-unexpected is my motto for development.