12 votes

Graph databases / Nosql with Mathematica

I have an open-source MongoDB Mathematica driver here: https://github.com/zbjornson/MongoDBLink. There are quick setup instructions and an overview in the readme. It's built on the official Java ...
ZachB's user avatar
  • 1,200
9 votes

How to use Mathematica in AWS cloud?

Install version 11.3 of the player, write your script.wl and run wolframscript -f script.wl If you want a GUI check https://...
Fortsaint's user avatar
  • 2,060
8 votes

Finding the frequency of letters in a string

Why not use LetterCounts LetterCounts[sentence, IgnoreCase -> True] // KeySort N[#]/Total[#] &[%] ...
Αλέξανδρος Ζεγγ's user avatar
7 votes

Build API without the WolframCloud?

Currently APIFunction / CloudDeploy works only with the Public Cloud or an Enterprise Private Cloud. So either you need an EPC ...
6 votes

Graph databases / Nosql with Mathematica

Wolfram Language version 11.3 now has support for interfacing with MongoDB. You can connect to a MongoDB database via MongoConnect. For example, connecting to a ...
Sebastian's user avatar
  • 3,479
6 votes

How to put a loop in a loop

Define random using SetDelayed so that each time it is used it gives a different random vector: ...
kglr's user avatar
  • 392k
6 votes
Accepted

Jacobian matrix evaluation at a point

Let f be a vector function: f[x_, y_] := {f1[x, y], f2[x, y]}; Then the Jacobian is the matrix valued function: D[f[x, y], {{x, y}}] and the Jacobian at point {a,b} is: ...
Daniel Huber's user avatar
5 votes
Accepted

How to make a matrix that had diffrentation without functions

One possiblity is to define the function d as: d = {{D[#, x], 0}, {0, D[#, y]}, {D[#, x], D[#, y]}} & To apply this operator to a particular function: ...
bill s's user avatar
  • 68.8k
5 votes

webmathematica to share my game?

This applies to any Wolfram Cloud based web application, not simply to your question, but there are say 4 steps involved in creating a web app. Hopefully some of this carries over from WC to ...
b3m2a1's user avatar
  • 46.8k
5 votes

Jacobian matrix evaluation at a point

You can do it as follows: Vector field: F[{x_, y_}] := Evaluate[{f1[x, y], f2[x, y]}] X = {x, y}; X0 = {a, b}; The Jacobian Matrix: ...
E. Chan-López's user avatar
5 votes

How do I create cobweb iterations or stair steps **WITH ARROWS** to show attractive and repulsive fixed points for a graph?

If we have two functions that we're "bouncing" between, then at each step we can solve for how to move horizontally or vertically from one function to the other. We need to know whether for ...
lericr's user avatar
  • 26.4k
4 votes

Creating REST Web Service with webMathematica

If you have a look at the "webMathematica/Examples/PlotScript/PlotScript.jsp" example : ...
Gautam Anand's user avatar
4 votes

Build API without the WolframCloud?

Now there's WolframWebEngine which allows one to create a sort of personal wolfram cloud.
Fortsaint's user avatar
  • 2,060
4 votes

Finding the frequency of letters in a string

Use LetterCounts as in Αλέξανδρος Ζεγγ's answer: lc = KeySort @ LetterCounts[sentence, IgnoreCase -> True] To get the ...
kglr's user avatar
  • 392k
4 votes

Jacobian matrix evaluation at a point

If you have a look at this link you can take the code as appears there. Namely, ...
bmf's user avatar
  • 14.9k
4 votes

I need help in complements of subsets

You have too many braces in TTt. Note also, you should not use uppercase names, because these are used by the system. Here is working code: ...
Daniel Huber's user avatar
4 votes

I need help in complements of subsets

We could also use DeleteElements (new in 13.1) a = {{P1}, {P2, P3}}; b = {P1, P2, P3, P4}; DeleteElements[b, #] & /@ a {P2,...
eldo's user avatar
  • 61.3k
3 votes

Compute the polynomial interpolation of the points (xi, 1/(1 + x^2)) for xi = −2, 1, 0, 1, 2

...
flinty's user avatar
  • 24.8k
3 votes

Graph not plotting any points

If your plot doesn't show anything, it's often helpful to look what your plotted function does. If you evaluate e.g. f[1] in your notebook, you'll see: -1 + ln[1]...
Niki Estner's user avatar
  • 36.1k
3 votes

How to calculate this limit?

As simple as using Limit: Clear[n]; Limit[n^2 ((1 + 1/(1 + n))^(n + 1) - (1 + 1/n)^n), n -> ∞] (*E/2*)
Subho's user avatar
  • 1,534
3 votes

How do I create cobweb iterations or stair steps **WITH ARROWS** to show attractive and repulsive fixed points for a graph?

Clear["Global`*"] Without the arrows just use ResourceFunction["CobwebPlot"] ...
Bob Hanlon's user avatar
  • 155k
2 votes

How to select bottom three "norm" values and their corresponding matrices?

Get rid of the Subscript's. They look nice, but they make calculations with lists impossible. Store lists of values as lists of values, matrices as lists of lists, ...
Niki Estner's user avatar
  • 36.1k
2 votes
Accepted

How to display a True/False table

One could use a mixture of Table, Cases and If to produce the desired result. Here are the ...
Jack LaVigne's user avatar
  • 14.4k
2 votes

Plotting a few Maclaurin Series in Mathematica

Here's one way: Plot[ Evaluate@Normal@Series[{Exp[Sin[x]], (x^2 + Exp[x])^(-1), Exp[-4 x^2 + 5 x]}, {x, 0, 5}], {x, -1/2, 1/2}]
Michael E2's user avatar
  • 234k
2 votes

Use FIT to calculate regression line from two sets of data

The way the question is phrased you have two lists that need to be joined and then apply a linear fit to the joined list. To join them use: ...
Jack LaVigne's user avatar
  • 14.4k
2 votes

Finding the frequency of letters in a string

Does this not accomplish what you're after? Reverse[SortBy[ Tally[ToLowerCase@ StringCases[sentence, LetterCharacter]], #[[2]] &]]
ktm's user avatar
  • 4,232
2 votes
Accepted

Plot streamplot for two stability point for Jacobian

Without your function we can't give a full answer, but this should suffice: ...
David G. Stork's user avatar
2 votes
Accepted

Graphing and calculating the volume using mathematica (or other)

A possible general approach (not fully verified or optimized). The strategy is as follow: Position the solid and cutting cylinders (also solid in my case). Move the cutting cylinder along its axis ...
Jean-Pierre's user avatar
  • 5,187
1 vote

Manipulating the plots obtained from NDSolve

It is bad practice and dangerous to use the same symbol name in the ODE and for the solution function. Anyway, with the code below you can play with your parameters. ...
Daniel Huber's user avatar

Only top scored, non community-wiki answers of a minimum length are eligible