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Top new questions this week:

Mathematica v12 Integration bug?

After upgrading to mathematica 12, this integral gives the wrong result, also with other types of similar integrals. Integrate[t[2]*Exp[t[2]],t[2]] The output Exp[t[2]^2]/2 is wrong (it should ...

version-12  
asked by mastrok 15 votes

Why use \[FormalN]?

Through a copy of some code from an answer on this site I discovered the existence of: \[FormalN] The documentation describes it as follows: "Used to represent a formal parameter that will never ...

programming documentation  
asked by nilo de roock 15 votes
answered by Sjoerd Smit 15 votes

Convert symbolic to numeric code: speed up morphing

Recently I asked a question about the morphing between two functions and got two excellent answers. The accepted answer is using the continuous optimal transport theory. This seems to be very suitable ...

equation-solving numerical-integration  
asked by yarchik 12 votes
answered by Federico 9 votes

How to fill a closed parametric curve?

I have a curve in parametric form: ParametricPlot[{(1 - Cos[2 \[Pi] s]) Sin[2 \[Pi] s], Cos[2 \[Pi] s] (Sin[2 \[Pi] s] + 1)}, {s, 0, 1}, Axes -> False, PlotStyle -> Black] This gives: ...

plotting filling  
asked by tst 11 votes
answered by kglr 17 votes

Simplify makes Mathematica forget that a matrix is Hermitian

Using Simplify with certain trivial assumptions makes Mathematica forget that a given matrix is Hermitian. See the minimal example below: expr = Exp[I*2*π*Re[n]] mat = {{Re[n], a*expr}, ...

matrix simplifying-expressions linear-algebra assumptions  
asked by Hannebambel 8 votes
answered by mikado 8 votes

Can Mathematica achieve this diagram?

Can Mathematica be used to create diagrams of drift diffusion of the kind shown, including histograms showing the response-time distributions? The distributions capture the time taken by a random ...

plotting histograms  
asked by user120911 8 votes
answered by Michael E2 16 votes

Reverse color of overlapping points?

Is there a simple way to change the color of the region where two Points overlap? For example in Graphics[{PointSize[2], Point[{1, 1}], Point[{0, 0}]}], the resulting two points have an area where ...

plotting graphics  
asked by Nicholas G 7 votes
answered by Carl Woll 5 votes

Greatest hits from previous weeks:

Even Fibonacci numbers

Today, I found the Euler Project. Problem #2 is Each new term in the Fibonacci sequence is generated by adding the previous two terms. By starting with 1 and 2, the first 10 terms will be: 1, ...

number-theory project-euler  
asked by xyz 34 votes
answered by rcollyer 45 votes

Can Mathematica do symbolic linear algebra?

For instance, is there some way I can say "let A and B be arbitrary real $m\times n$ and $k\times m$ matrices, Simplify[Transpose[Transpose[A].Transpose[B]]]" and Mathematica would simplify it to B.A? ...

linear-algebra symbolic  
asked by Niki Estner 57 votes
answered by Mauricio de Oliveira 15 votes

How to plot an ellipse?

I'm new to Mathematica, and I'm finding it difficult to plot an ellipse. I tried using Plot[(x/5)^2 + (y/3)^2 == 1, {x, -5, 5}, {y, -3, 3}] but I'm getting some errors. Is there something wrong ...

plotting  
asked by Sriram 15 votes
answered by Jens 26 votes

Multivariable Taylor expansion does not work as expected

The basic multivariable Taylor expansion formula around a point is as follows: $$ f(\mathbf r + \mathbf a) = f(\mathbf r) + (\mathbf a \cdot \nabla )f(\mathbf r) + \frac{1}{2!}(\mathbf a \cdot ...

calculus-and-analysis series-expansion  
asked by matheorem 53 votes
answered by Jens 59 votes

Help find a bright object on Mars!

In today's news, scientists found a bright object on one of Curiosity's photos (it's near the bottom of the picture below). It's a bit tricky to find - I actually spent quite some time staring at the ...

image-processing  
asked by Victor K. 197 votes
answered by Niki Estner 256 votes

How to add a front-end to the free Wolfram Engine?

https://blog.stephenwolfram.com/2019/05/launching-today-free-wolfram-engine-for-developers/ http://www.wolfram.com/engine/ The Free Wolfram Engine for Developers is available for pre-production ...

front-end jupyter-notebook  
asked by Alexey Golyshev 51 votes
answered by Alexey Golyshev 46 votes

How to express trigonometric equation in terms of of given trigonometric function?

How can I express a trigonometric equation / identity in terms of a given trigonometric function? using following trigonometric identities Sin[x]^2+Cos[x]^2==1 Sin[x]/Cos[x]==Tan[x] ...

functions trigonometry  
asked by Prashant Bhate 30 votes
answered by Simon 37 votes

Can you answer these questions?

Access to quantities other than parameter values in in StepMonitor for NonlinearModelFit?

NonlinearModelFit obviously does a lot of internal calculations at each step, including determining the Response (the value of the fitting function for the current values of the parameters evaluated ...

nonlinear monitoring  
asked by Kevin Ausman 1 vote

The replacement function is an integral and the double integral yields a different answer than the normal double integral

I am fairly new to Mathematica. I have a quick inquiry. The code is simple and just 3 lines. Trying to do a replacement rule as follows ruletrr = intsl[exp_] :> Integrate[exp, {u, u, 1}] ...

replacement  
asked by Ehab Wilson 1 vote

Why does FindInstance take so long: It is faster with more restrictions than with less?

A support case with the identification [CASE:4347836] was created. I just noted this little puzzle on twitter by Brillant.org: \begin{align} A B C\\+ BCA\\ = CDE \end{align} Given that $A$ is ...

equation-solving error findinstance  
asked by gwr 3 votes
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